How to measure height of an airplane?

[Joe Harrison]

Say you are on the ground and want to measure the altitude of a plane that
is going over your head, what (simple) equipment can you use? They are
supposed to maintain at least 500 feet where I am but I don't believe they
actually do. Tired of endless stream of noisy planes (helicopters the worst
actually) when I'm pottering around in the garden.

I phoned the Civil Aviation Authority last year but although polite they
were pretty unhelpful. Basically said well it's up to you to make a case and
prove these things are too low. Now it looks like we're into low-flying
season again so wondering what I could do.

[Tim Ward]

Post by Joe Harrison
Say you are on the ground and want to measure the altitude of a plane that
is going over your head, what (simple) equipment can you use? They are
supposed to maintain at least 500 feet where I am but I don't believe they
actually do. Tired of endless stream of noisy planes (helicopters the
worst actually) when I'm pottering around in the garden.

Primary school trig. Take two simultaneous bearings from different places
with a decent intercept angle and do the sums. (Oh, you have to know exactly
how far apart the two places are of course, to give you a baseline, but GPS
coordinates should be good enough.) Equipment is sticks and bits of string
and/or some means of measuring angles.

[Joe Harrison]

Post by Tim Ward

Post by Joe Harrison
Say you are on the ground and want to measure the altitude of a plane
that is going over your head, what (simple) equipment can you use?

Primary school trig. Take two simultaneous bearings from different places
with a decent intercept angle and do the sums. ...sticks and bits of
string

Hmm it sounds hard, I mean these things do move quite fast. Ta for thought
however.

I don't know anything about aviation and I imagined altitude measurement
might be a routine task with a well-known solution. Any other thoughts
welcome on how I convince CAA to do something.

[Edward]

Post by Joe Harrison

Post by Tim Ward

Post by Joe Harrison
Say you are on the ground and want to measure the altitude of a plane
that is going over your head, what (simple) equipment can you use?

Primary school trig. Take two simultaneous bearings from different places
with a decent intercept angle and do the sums. ...sticks and bits of
string

Hmm it sounds hard, I mean these things do move quite fast. Ta for thought
however.
I don't know anything about aviation and I imagined altitude measurement
might be a routine task with a well-known solution. Any other thoughts
welcome on how I convince CAA to do something.

Gunnery experts use rangefinders which seem reasonably portable. It
looks like a binocular with the lenses about a metre apart.

Try a forces surplus specialist?

[Ric]

Can I ask you when the airfield that is evidently near you was built?

And when did you buy your house?

I have every sympathy for you if the former was built after the latter.

[John L]

Post by Joe Harrison
Say you are on the ground and want to measure the altitude of a plane that
is going over your head, what (simple) equipment can you use? They are
supposed to maintain at least 500 feet where I am but I don't believe they
actually do. Tired of endless stream of noisy planes (helicopters the worst
actually) when I'm pottering around in the garden.

Unless you are on the final approach path of an airfield then it's VERY
unlikely that aircraft are getting closer than 500ft. The 500ft rule
does not apply on take-off or landing, for obvious reasons but even so
you'd have to be within a mile of the airfield for departing/arriving
aircraft to be below 500ft.

It is notoriously difficult to judge the height of aircraft and it is
commonplace that people on the ground think they are much lower than
they actually are. As a light aircraft pilot, I can tell you that there
is no way I want to be flying within 500ft of ANYTHING apart from the
runway I am about to land on!

John.

[Joe Harrison]

Post by John L
Unless you are on the final approach path of an airfield then it's VERY
unlikely that aircraft are getting closer than 500ft.
It is notoriously difficult to judge the height of aircraft and it is
commonplace that people on the ground think they are much lower than they
actually are.

OK, well I have no idea how far 500 feet actually is but these things look
so low I just assumed they must be less. Maybe you are right then I will
have to think about it. I work in a ten-storey building so I will ask our
admin what the height is and see if I can imagine it from that.

In reply to Ric and your point above I don't live near an airport. According
to the bloke at the CAA the reason I see all this traffic is that I am
exactly on the western edge of the no-fly-zone for Heathrow, which
apparently means everyone flies just slightly outside it, which just so
happens to be right over my house. It never used to be so busy so I suspect
they have created this zone thing in the last few years.

I actually quite like airplanes but it is just so annoying when you're in
the garden pruning the squirrels and something goes belting overhead,
especially when 10-1 it's some fat bastard taking his girlfriend to Ascot or
what have you. Incidentally it is always small planes and helicopters, there
are plenty of big ones really going to Heathrow but they are quieter and
higher up and not a problem. I don't know if it's my imagination but I think
I've seen a lot of ancient (WW2) planes over Easter, maybe going to air
shows or something.

When I talked to the CAA last year the guy asked what their registration
numbers were so I wrote down a few and rang him back. I assumed it was like
cars and police but in fact all he then did was tell me the postal address
of the owners and told me to take it up with them.

[John L]

There's no such thing as a "no fly zone for Heathrow". There IS a large
area of Class-A airspace over London, the London CTR, which generally
has to be avoided by General Aviation (i.e. non commercial stuff). Its
western boundary is an arc from just SW of High Wycombe, south to White
Waltham then Bracknell and finally Bagshot. In this general area there
is further class-A airspace at 2500ft+ meaning that most aircraft will
fly below 2500ft.

However, there are two key rules that ALL aircraft must obey except on
take-off and landing. One is that no aircraft may be closer than 500ft
to any object or person. The other is that in a built up area no
aircraft may be lower than 1000ft or, if higher, whatever height is
needed to be able to glide clear (e.g. to a field) in the event of
engine failure.

The upshot of this is that I would expect aircraft to be cruising at
between 1500ft and 2400ft in the area you are referring to. Of course
there are several airfields in the general area of the western edge of
the London CTR. For example, White Waltham near Maidenhead is a major GA
airfield, as is Blackbushe near Camberley. It may be that lower aircraft
are inbound to or recently departed from one of these long established
airfields.

I'm afraid that your comment that you "actually quite like airplanes
[sic]" is considerably undermined by your utterly inaccurate
characterisation of general aviation as "10-1 it's some fat bastard
taking his girlfriend to Ascot or what have you". Why not find your way
to your local General Aviation airfield and find out about the sort of
people, people just like you and me, that fly these light aircraft?

John.

Post by Joe Harrison
OK, well I have no idea how far 500 feet actually is but these things look
so low I just assumed they must be less. Maybe you are right then I will
have to think about it. I work in a ten-storey building so I will ask our
admin what the height is and see if I can imagine it from that.
In reply to Ric and your point above I don't live near an airport. According
to the bloke at the CAA the reason I see all this traffic is that I am
exactly on the western edge of the no-fly-zone for Heathrow, which
apparently means everyone flies just slightly outside it, which just so
happens to be right over my house. It never used to be so busy so I suspect
they have created this zone thing in the last few years.
I actually quite like airplanes but it is just so annoying when you're in
the garden pruning the squirrels and something goes belting overhead,
especially when 10-1 it's some fat bastard taking his girlfriend to Ascot or
what have you. Incidentally it is always small planes and helicopters, there
are plenty of big ones really going to Heathrow but they are quieter and
higher up and not a problem. I don't know if it's my imagination but I think
I've seen a lot of ancient (WW2) planes over Easter, maybe going to air
shows or something.
When I talked to the CAA last year the guy asked what their registration
numbers were so I wrote down a few and rang him back. I assumed it was like
cars and police but in fact all he then did was tell me the postal address
of the owners and told me to take it up with them.

[Joe Harrison]

Post by John L
The upshot of this is that I would expect aircraft to be cruising at
between 1500ft and 2400ft in the area you are referring to.

I am indeed in Bracknell and do not believe 1500-2400 feet correctly
characterises the altitude of the bits of metal traveling over my particular
corner of housing estate. I could accept that maybe I mistakenly identified
these planes as below 500 feet when they actually were not, but I can't
believe I could get it wrong to 1500+ feet.

Post by John L
Of course there are several airfields in the general area of the western
edge of the London CTR. For example, White Waltham near Maidenhead is a
major GA airfield, as is Blackbushe near Camberley. It may be that lower
aircraft are inbound to or recently departed from one of these long
established airfields.

Possibly but the nuisance to which I am referring is along the lines of one
every few minutes for extended periods. (Although of course I only notice
them when it's daytime and then only during fine weather.) I do in fact
visit Blackbushe reasonably frequently (for its car auctions) and although I
have not paid much attention to the aviation area I must say that in
contrast takeoffs and landings appear sporadic and infrequent.

Post by John L
I'm afraid that your comment that you "actually quite like airplanes
[sic]" is considerably undermined by your utterly inaccurate
characterisation of general aviation as "10-1 it's some fat bastard taking
his girlfriend to Ascot or what have you". Why not find your way to your
local General Aviation airfield and find out about the sort of people,
people just like you and me, that fly these light aircraft?

I do like planes in general and I don't identify myself with the well-known
groups of people who live near airports and campaign vocally about the
associated inconveniences. Whilst I appreciate that some people enjoy flying
small planes for pleasure I do feel that especially in the case of
helicopters the horrendous expense more likely implies convenience of
business or personal transport. Perhaps my Ascot reference was a bit over
the top and motivated by too much exposure to the gross behaviour of its
racegoers.

As an outsider to the business of flying my naive impression of air travel
is a system of mindless but strictly-enforced rules and regulations (I even
had my duty-free booze confiscated a couple of months ago due to
contravening some bizarre piece of airport red tape!) In this context I am
cross that the supposed regulators are not very bothered when I report what
I think is people flying much lower than they are supposed to.

[Peter]

Post by Joe Harrison
I do like planes in general and I don't identify myself with the well-known
groups of people who live near airports and campaign vocally about the
associated inconveniences. Whilst I appreciate that some people enjoy flying
small planes for pleasure I do feel that especially in the case of
helicopters the horrendous expense more likely implies convenience of
business or personal transport. Perhaps my Ascot reference was a bit over
the top and motivated by too much exposure to the gross behaviour of its
racegoers.

There are people like that in GA but they probably amount to under 1%
of pilots. The best place to find them is propping up the airport bar,
anyway, not anywhere airborne.

The wealthy Ascot regulars will have a paid commercial crew to fly the
aircraft!

[Tim Ward]

I can't believe I could get it wrong to 1500+ feet.

I can. It happens all the time.

I am
cross that the supposed regulators are not very bothered when I report what
I think is people flying much lower than they are supposed to.

They are not very bothered because the vast majority of such reports are,
experience has shown, simply wrong.

[Jeroen Wenting]

Post by Tim Ward

I can't believe I could get it wrong to 1500+ feet.

I can. It happens all the time.

And often deliberately... Schiphol has to deal with fake complaints
constantly. People are paid by the anti-aviation/environmentalist lobby to
check teletext for departures and phone in a noise complaint 5 minutes
later.
Of course most of those people are not the brightest so they get complaints
about aircraft departing to the south from locations a hundred or more
kilometers to the north at times when that aircraft couldn't have reached
the point the complaint originated from even if it had been flying north
instead of south...

When questioned those people also claim they're not against aircraft, just
against the noise and the fact that people use them that shouldn't (meaning
anyone but they themselves).

[Woody]

A simple Google Earth check shows White Waltham is only 5 miles north of the
center of Bracknell and Blackbush is only seven miles southwest of Bracknell
so there is probably a fair amount of general aviation traffic. Get use to
it as there is nothing that can be done about it. Find something else to
complain about like the noisy motorcycles....

Post by Joe Harrison

Post by John L
The upshot of this is that I would expect aircraft to be cruising at
between 1500ft and 2400ft in the area you are referring to.

I am indeed in Bracknell and do not believe 1500-2400 feet correctly
characterises the altitude of the bits of metal traveling over my
particular corner of housing estate. I could accept that maybe I
mistakenly identified these planes as below 500 feet when they actually
were not, but I can't believe I could get it wrong to 1500+ feet.

Post by John L
Of course there are several airfields in the general area of the western
edge of the London CTR. For example, White Waltham near Maidenhead is a
major GA airfield, as is Blackbushe near Camberley. It may be that lower
aircraft are inbound to or recently departed from one of these long
established airfields.

Possibly but the nuisance to which I am referring is along the lines of
one every few minutes for extended periods. (Although of course I only
notice them when it's daytime and then only during fine weather.) I do in
fact visit Blackbushe reasonably frequently (for its car auctions) and
although I have not paid much attention to the aviation area I must say
that in contrast takeoffs and landings appear sporadic and infrequent.

Post by John L
I'm afraid that your comment that you "actually quite like airplanes
[sic]" is considerably undermined by your utterly inaccurate
characterisation of general aviation as "10-1 it's some fat bastard
taking his girlfriend to Ascot or what have you". Why not find your way
to your local General Aviation airfield and find out about the sort of
people, people just like you and me, that fly these light aircraft?

I do like planes in general and I don't identify myself with the
well-known groups of people who live near airports and campaign vocally
about the associated inconveniences. Whilst I appreciate that some people
enjoy flying small planes for pleasure I do feel that especially in the
case of helicopters the horrendous expense more likely implies convenience
of business or personal transport. Perhaps my Ascot reference was a bit
over the top and motivated by too much exposure to the gross behaviour of
its racegoers.
As an outsider to the business of flying my naive impression of air travel
is a system of mindless but strictly-enforced rules and regulations (I
even had my duty-free booze confiscated a couple of months ago due to
contravening some bizarre piece of airport red tape!) In this context I am
cross that the supposed regulators are not very bothered when I report
what I think is people flying much lower than they are supposed to.

[Tim Ward]

According to the bloke at the CAA the reason I see all this traffic is
that I am exactly on the western edge of the no-fly-zone for Heathrow,
which apparently means everyone flies just slightly outside it, which just
so happens to be right over my house.

If by "no-fly-zone for Heathrow" you mean the London CTR then the airspace
above you is uncontrolled up to 2500'. Now, that's 2500' above sea level, so
depending on exactly where you live that might be as little as 2150' above
ground level.

In such an area most light aircraft would want to fly as high as they could,
with perhaps a little margin so that a moment's inattention on hitting an
unexpected thermal doesn't throw them up into controlled airspace, so they
might be aiming at 2200', possibly as low as 1850' above ground level
depending on where you live.

But ... the airspace round there is going to be a bit crowded, so some
pilots will think it safer to fly lower down away from the crowds, maybe
down to around 1200' above ground level.

(All this assuming that you aren't actually living under the White Waltham
circuit, of course, in which case 600' could be routine.)

Note also that some pilots are bound by stricter rules than the 500' rule -
if I am forced to fly less than 1000' above ground level I have to explain
myself to an instructor when I get back, according to the contract under
which I rent the aircraft. (It hasn't happened, but if it did I would expect
a severe bollocking for taking off in unsuitable weather.)

[Geo]

On Mon, 09 Apr 2007 21:34:51 GMT, "Joe Harrison" <***@crylo.com> wrote:

<snip>

Post by Joe Harrison
When I talked to the CAA last year the guy asked what their registration
numbers were so I wrote down a few and rang him back. I assumed it was like
cars and police but in fact all he then did was tell me the postal address
of the owners and told me to take it up with them.

Were you able to read the aircraft registrtion letters without binoculars?
This might give someone a clue regarding distance since the letters should be
50cm high (unless the wing is too small.

Geo

[Joe Harrison]

Post by Geo
Were you able to read the aircraft registrtion letters without binoculars?
This might give someone a clue regarding distance since the letters should be
50cm high (unless the wing is too small.

This is a very good point and the answer is "sometimes." With helicopters I
have never ever seen a registration. With regular planes I can sometimes see
the letters no problem but other times not. Having said that it's
complicated by my distance vision not being all it used to be and I have
been experimenting with some new glasses recently after one eye was ruled
not good enough unaided to drive a car with.

There has been some real food for thought in this thread, in particular I
live at the top of a hill which previously I had not considered to be a
factor. Absolutely no planes at all this evening for some reason but I'll
look more carefully at what happens at the weekend. I suppose if the
popularity of flying over my house turns out to be completely legit I will
have to grin and bear it.

[Simon Hobson]

Post by Joe Harrison
OK, well I have no idea how far 500 feet actually is but these things look
so low I just assumed they must be less. Maybe you are right then I will
have to think about it. I work in a ten-storey building so I will ask our
admin what the height is and see if I can imagine it from that.

As for your building, you should be able to get a reasonable estimate of
floor height, then multiply by ten !

Post by Joe Harrison
I actually quite like airplanes but it is just so annoying when you're in
the garden pruning the squirrels and something goes belting overhead,

I agree, the noise can be very intrusive and noticably different between
aircraft. I try to be as considerate as I can when I'm flying, unfortunately
I think there are a significant number of pilots who've never even considered
it.

Something else you may be interested in, though it doesn't really help you.
There are in fact a number of well known ways to significantly reduce the
noise from small piston aircraft which are what most of these will be - but
the way the regulatory system is run makes them VERY expensive to fit, so
expensive that few owners would be able to afford it if they wanted to. I
personally know someone who imported a plane from Germany fitted with one of
these "hush kits" (different propellor and exhaust system) and replaced it
with standard parts (at a cost of about £3k IIRC) because the cost of having
it approved by the CAA would have been much higher. We are SUPPOSED to have a
unified regulatory system across Europe, and were supposed to have had when
this occurred.

When I part owned a plane I would have liked to have "done my bit" to reduce
my impact on those below, but with the costs involved I didn't even bother
raising the issue with the other 9 people as the cost, even when split 10
ways, would have been well past anything we could justify.

Post by Joe Harrison
When I talked to the CAA last year the guy asked what their registration
numbers were so I wrote down a few and rang him back. I assumed it was like
cars and police but in fact all he then did was tell me the postal address
of the owners and told me to take it up with them.

Well if you can go along with evidence then they can be very hard on a pilot
- stories abound of their heavy handed approach. However, as someone else has
pointed out, experience shows that it's very difficult to judge height from
the ground - mostly because you have no frame of reference.


Someone has already suggested you pop along to the local airfield. I'd go
further and suggest that if you find a friendly club and explain who you
are/why you are there, then you'll almost certainly find people that will be
happy to take you up to see the situation from the air. I don't know what the
places down there are like, but I would hope that they'd be that friendly.


One final thing, hopefully to dispel one of the common myths - not all
aircraft owners are rich. To put it in perspective, some of those aircraft
flying overhead are worth as little as £15k - look along most streets and
you'll see plenty of cars in that sort of value range. My share of a plane
was worth about £4k, so less than most people have invested in their cars.
Yes there are MUCH more valuable aircraft, but as value goes up, numbers come
down. Running costs are a different matter of course :-(

[Tim Ward]

Post by Simon Hobson
One final thing, hopefully to dispel one of the common myths - not all
aircraft owners are rich.

Indeed. The typical picture is of someone who cycles to the airfield in
clothes full of holes and flies an old banger which takes all his money -
none left for running a car or buying clothes.

And of course most pilots aren't aircraft owners, they rent by the hour.

[Jeroen Wenting]

Post by John L

Post by Joe Harrison
Say you are on the ground and want to measure the altitude of a plane
that is going over your head, what (simple) equipment can you use? They
are supposed to maintain at least 500 feet where I am but I don't believe
they actually do. Tired of endless stream of noisy planes (helicopters
the worst actually) when I'm pottering around in the garden.

Unless you are on the final approach path of an airfield then it's VERY
unlikely that aircraft are getting closer than 500ft. The 500ft rule does
not apply on take-off or landing, for obvious reasons but even so you'd
have to be within a mile of the airfield for departing/arriving aircraft
to be below 500ft.

It also doesn't apply to helicopters... They're excluded from altitude
restrictions.

Post by John L
It is notoriously difficult to judge the height of aircraft and it is
commonplace that people on the ground think they are much lower than they
actually are. As a light aircraft pilot, I can tell you that there is no
way I want to be flying within 500ft of ANYTHING apart from the runway I
am about to land on!

Correct.
If you know the exact type of aircraft you can of course do the math. Look
at the aircraft with a stick of known length next to your eye. You now know
the relative size of the aircraft to the stick.
From that you can derive the size of the aircraft as perceived due to
distance. Knowing the real size you can calculate the distance from that.

[Al G]

Post by Joe Harrison
Say you are on the ground and want to measure the altitude of a plane that
is going over your head, what (simple) equipment can you use? They are
supposed to maintain at least 500 feet where I am but I don't believe they
actually do. Tired of endless stream of noisy planes (helicopters the
worst actually) when I'm pottering around in the garden.
I phoned the Civil Aviation Authority last year but although polite they
were pretty unhelpful. Basically said well it's up to you to make a case
and prove these things are too low. Now it looks like we're into
low-flying season again so wondering what I could do.

The model rocket folks use 2 people with small plastic sextants, and
some tables. I do believe they are assuming the rocket is directly over the
launch point.

Al G

[Peter]

Post by Joe Harrison
Say you are on the ground and want to measure the altitude of a plane that
is going over your head, what (simple) equipment can you use? They are
supposed to maintain at least 500 feet where I am but I don't believe they
actually do. Tired of endless stream of noisy planes (helicopters the worst
actually) when I'm pottering around in the garden.

Apart from trigonometry there is no way you can tell accurately.

If however there is say a 500ft hill (that is, a 500ft projection
**above the surrounding ground**) and you see an aircraft fly below
the top of that hill, and you are standing on the ground, then
obviously he must have been lower than 500ft above the ground.

Obviously if all ground around you is flat, there is no way you can do
this.

Many people come to a court accused of low flying, and nearly all get
acquitted, because it's easy to show that Joe Public is a very poor
judge of height.

Most fixed wing pilots will be nowhere near that low. It's hard work
flying that low and is pretty pointless. Helicopters do go lower than
fixed wing, on average.

[Edward]

Post by Peter
Many people come to a court accused of low flying, and nearly all get
acquitted, because it's easy to show that Joe Public is a very poor
judge of height.
Most fixed wing pilots will be nowhere near that low. It's hard work
flying that low and is pretty pointless. Helicopters do go lower than
fixed wing, on average.

I agree we laymen are poor judges of height. As a Snowdonia farmer, I
am no stranger to low flying by forces aircraft. I have looked Hercules
pilots in the eye and received waves from the crewmen in the door. I
have stood above a Canberra and watched it fly down the valley with the
bomb doors (?) open. I have dropped my motorbike and stood aghast as I
watched a near miss by 2 Gnats. Neither took avoiding action so I
presume neither saw the other. My heart was going like a trip hammer
afterwards.

But the most extraordinary thing I have seen was a GA single engine pass
near the farmyard where I was working. The yard is at 400', the valley
floor is 350' the hill opposite is 350 yards away and the top is 650'
all measured off the OS map afterwards. It passed between me and the
hill with the top showing well above it.

[Tim Ward]

Post by Edward
But the most extraordinary thing I have seen was a GA single engine pass
near the farmyard where I was working. The yard is at 400', the valley
floor is 350' the hill opposite is 350 yards away and the top is 650'
all measured off the OS map afterwards. It passed between me and the
hill with the top showing well above it.

Well, there might have been a good reason, and if not *you* do get the
*occasional* idiot playing silly buggers, none of us is going to deny that.

[Jeroen Wenting]

Post by Tim Ward

Post by Edward
But the most extraordinary thing I have seen was a GA single engine pass
near the farmyard where I was working. The yard is at 400', the valley
floor is 350' the hill opposite is 350 yards away and the top is 650'
all measured off the OS map afterwards. It passed between me and the
hill with the top showing well above it.

Well, there might have been a good reason, and if not *you* do get the
*occasional* idiot playing silly buggers, none of us is going to deny that.

like cropdusting. This was after all a farm...
Cropdusters need to fly very low over the fields they're servicing to
prevent the aerosol from becoming too diluted. They regularly have to climb
to avoid powerlines and trees...

[Edward]

Post by Jeroen Wenting

Post by Tim Ward

Post by Edward
But the most extraordinary thing I have seen was a GA single engine pass
near the farmyard where I was working. The yard is at 400', the valley
floor is 350' the hill opposite is 350 yards away and the top is 650'
all measured off the OS map afterwards. It passed between me and the
hill with the top showing well above it.

Well, there might have been a good reason, and if not *you* do get the
*occasional* idiot playing silly buggers, none of us is going to deny that.

like cropdusting. This was after all a farm...
Cropdusters need to fly very low over the fields they're servicing to
prevent the aerosol from becoming too diluted. They regularly have to climb
to avoid powerlines and trees...

You only get choppers spraying bracken here. There are no crops as such
to need dusting. I did see a fixed wing plane spraying aphids in a corn
crop in Anglesey. Today the Environment Agency has put a stop to all
fixed wing spraying in Britain AFAIK.

[Chris.Cheney]

Post by Joe Harrison
Say you are on the ground and want to measure the altitude of a plane
that is going over your head, what (simple) equipment can you use?
They are supposed to maintain at least 500 feet where I am but I don't
believe they actually do. Tired of endless stream of noisy planes
(helicopters the worst actually) when I'm pottering around in the
garden.
I phoned the Civil Aviation Authority last year but although polite
they were pretty unhelpful. Basically said well it's up to you to make
a case and prove these things are too low. Now it looks like we're
into low-flying season again so wondering what I could do.

Measure the wingspan or fuselage length using vernier calipers at arms
length. www.caa.co.uk/ginfo will tell you the aircraft type from the (UK)
registration mark, Find the actual wingspan or fuselage length from
published aircraft data for the type (use Google).

E.g. a Cessna 150/152 wingspan (10.17 metres) at a height of 500 ft (150
metres) would be equivalent at arms length (say 635 mm from the eye), to
10.17 * 635 / 150 = 43.05 mm for someone on the ground.

[Stephen]

Post by Chris.Cheney

Post by Joe Harrison
Say you are on the ground and want to measure the altitude of a plane
that is going over your head, what (simple) equipment can you use?
They are supposed to maintain at least 500 feet where I am but I don't
believe they actually do. Tired of endless stream of noisy planes
(helicopters the worst actually) when I'm pottering around in the
garden.

Measure the wingspan or fuselage length using vernier calipers at arms
length. www.caa.co.uk/ginfo will tell you the aircraft type from the (UK)
registration mark, Find the actual wingspan or fuselage length from
published aircraft data for the type (use Google).
E.g. a Cessna 150/152 wingspan (10.17 metres) at a height of 500 ft (150
metres) would be equivalent at arms length (say 635 mm from the eye), to
10.17 * 635 / 150 = 43.05 mm for someone on the ground.

A similar technique would be to take a picture of the aeroplane and then
calibrate the image size/object size ratio for a given distance with another
photo of something of known dimension and distance on the horizontal - which
should be easy to measure. Use the camera on it's maximum zoom so you can
reliably set the same zoom for your calibration. You'll also be able to
read the registration letters from the image to find out the aircraft type
and then size. If you can't read the registration letters from your image
then the aeroplane will be much higher than the minimum required.

Stephen

[Peter]

Post by Stephen
A similar technique would be to take a picture of the aeroplane and then
calibrate the image size/object size ratio for a given distance with another
photo of something of known dimension and distance on the horizontal - which
should be easy to measure. Use the camera on it's maximum zoom so you can
reliably set the same zoom for your calibration. You'll also be able to
read the registration letters from the image to find out the aircraft type
and then size. If you can't read the registration letters from your image
then the aeroplane will be much higher than the minimum required.

I should say that this kind of thing will never get you a conviction,
because rules on acquisition and handling of evidence.

A colleague had his car repeatedly vandalised by kids from a nearby
council estate. He set up video cameras and got the lot of them, red
handed, on video. He called in the police and the persons involved
were well known to them but it turned out this could not be used in
evidence, so he went for a civil action, and their parents settled out
of court. For evidence to count in a *criminal* case (which is what we
are talking about if somebody is to get done by the CAA for low
flying) it needs to be obtained by an independent party (a consultant
or a private detective, for example) and handled according to certain
rules.

You would also need to get the camera angle very accurate in order to
work out the height of the aircraft.

[Stephen]

Post by Peter
I should say that this kind of thing will never get you a conviction,
because rules on acquisition and handling of evidence.

The challenge here is not to secure a conviction but to convince the OP that
these aircraft are higher than he thinks.

Post by Peter
You would also need to get the camera angle very accurate in order to
work out the height of the aircraft.

If the aircraft was pretty much overhead then the error will be small.

Also, the 500ft rule is a distance not a height. If the aircraft is more
than 500ft from the OP then he's got nothing to complain about. Someone
else might have though.

Stephen

[Chris.Cheney]

Post by Peter

Post by Stephen
A similar technique would be to take a picture of the aeroplane and
then calibrate the image size/object size ratio for a given distance
with another photo of something of known dimension and distance on the
horizontal - which should be easy to measure. Use the camera on it's
maximum zoom so you can reliably set the same zoom for your
calibration. You'll also be able to read the registration letters
from the image to find out the aircraft type and then size. If you
can't read the registration letters from your image then the aeroplane
will be much higher than the minimum required.

I should say that this kind of thing will never get you a conviction,
because rules on acquisition and handling of evidence.

But it might demonstrate to the OP that the aircraft are at an adequate
height.

[me]

Post by Peter
You would also need to get the camera angle very accurate in order to
work out the height of the aircraft.

And you'd have to prove the zoom factor used and the position of the camera
at the time of the photograph and that the image had not been tampered with
and .....

I think all of this is worth doing if you need to convince yourself of the
height at which they're flying but, in the very unlikely event that lots of
pilots are stupid enough to be over Bracknell below 500 feet, you're going
to have your work cut out to get the CAA involved.

Incidentally, if you don't have a vernier rule, you can use a rule of thumb
(literally) to get a rough idea of the height. Most people's thumb (at the
fattest bit) subtends an angle of 2 degrees when held at their arm's length.
The thumb nail is about 1.5 degrees and the index finger nail is about 1
degree. The wings of a Cessna 172 at 500 feet would subtend 4.1 degrees
(arcsin (36ft /500ft) expressed in degrees), or about two thumb widths,
whereas at 1000 feet (a much more likely height) it would be about 2
degrees, or 1 thumb width - a big difference. This assumes the aircraft is
directly overhead, so you need to allow a bit for slant height, but you'll
get the idea. Most 2 and 4 seater light aircraft are close enough to the
size of a Cessna 172 (within say 20%) for these figures to give you a rough
idea of their height.

Eddie

[f***@eagletv.co.uk]

If you want to get an idea of what a light aircraft looks like at 500+ feet,
make a visit to your local airfield and take a look at the aircraft flying in
the circuit.

At White Waltham, for instance, circuits are flown at 800 feet above ground
level and follow the same pattern.

Generally speaking, after take off a light aircraft will climb to about 500+
feet before turning 90 degrees, usually to the left. It will continue to
climb till it reaches 800 feet. (More powerful aircraft will of course reach
800 feet rather quicker than slower ones.) The aircraft will then turn left
again so that it is now flying parallel - but in the opposite direction - to
the runway it took off on.

On this "downwind" leg of the circuit almost all aircraft should be flying at
800 feet above airfield level, before turning left again and beginning to
descend. (It is now on what's called "base leg" of the circuit.

By the time it turns left again and begins its final descent to the runway,
it will be at about 500 feet.

Of course not all circuits are flown as tidily as they should be, so there
must always be a bit of give and take in these figures. But at least it
might give you an idea of what the minima look like.

Well established, well managed airfields like White Waltham takes noise
abatement seriously and pass on complaints to identifiable pilots who break
the rules.

best,

Robert Eagle

Post by Joe Harrison
Say you are on the ground and want to measure the altitude of a plane that
is going over your head, what (simple) equipment can you use? They are
supposed to maintain at least 500 feet where I am but I don't believe they
actually do. Tired of endless stream of noisy planes (helicopters the worst
actually) when I'm pottering around in the garden.
I phoned the Civil Aviation Authority last year but although polite they
were pretty unhelpful. Basically said well it's up to you to make a case and
prove these things are too low. Now it looks like we're into low-flying
season again so wondering what I could do.

[Andy R]

Post by Joe Harrison
Say you are on the ground and want to measure the altitude of a plane that
is going over your head, what (simple) equipment can you use? They are
supposed to maintain at least 500 feet where I am but I don't believe they
actually do. Tired of endless stream of noisy planes (helicopters the
worst actually) when I'm pottering around in the garden.
I phoned the Civil Aviation Authority last year but although polite they
were pretty unhelpful. Basically said well it's up to you to make a case
and prove these things are too low. Now it looks like we're into
low-flying season again so wondering what I could do.

Shouldn't the subject be "How to measure the height of an aeroplane"?

I thought there was a citizenship test nowadays where immigrants had to show
a reasonable grasp of English before they could get a council house in
Bracknell. It's obviously not working.

Rgds

Andy R

[Peter]

Post by Andy R
I thought there was a citizenship test nowadays where immigrants had to show
a reasonable grasp of English before they could get a council house in
Bracknell. It's obviously not working.

For a council house in Bracknell, yes, but probably not for one in
Manchester ;)

[Jeroen Wenting]

Post by Andy R
Shouldn't the subject be "How to measure the height of an aeroplane"?
I thought there was a citizenship test nowadays where immigrants had to
show a reasonable grasp of English before they could get a council house
in Bracknell. It's obviously not working.

For immigrants maybe, sadly not for natives...