Low level helicopter routes over London
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Low level helicopter routes over London
Hello,
I live in central London and we regularly get helicopters flying low overhead and hovering. Usually pleasure flights and flights filming shots of the London skyline.
I've noticed quite a few 'single' helicopters - R22s and R44s, in addition to turbine machines.
I'm a fixed wing PPL and just curious as to the rationale behind allowing helicopters low level over London when fixed wing single aircraft are prohibited due to the 'glide clear' requirements. If the engine quit in the hover at 1000 feet how much forward distance could you cover in an autorotation? Less I would imagine than a fixed wing SEP in the same circumstances.
Would you aim to put it into the river if everything when quiet?
Thanks.
I live in central London and we regularly get helicopters flying low overhead and hovering. Usually pleasure flights and flights filming shots of the London skyline.
I've noticed quite a few 'single' helicopters - R22s and R44s, in addition to turbine machines.
I'm a fixed wing PPL and just curious as to the rationale behind allowing helicopters low level over London when fixed wing single aircraft are prohibited due to the 'glide clear' requirements. If the engine quit in the hover at 1000 feet how much forward distance could you cover in an autorotation? Less I would imagine than a fixed wing SEP in the same circumstances.
Would you aim to put it into the river if everything when quiet?
Thanks.
Last edited by taxistaxing; 10th Jan 2013 at 09:15.
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The land clear requirement for helicopters is abated because properly handled, they can land without the engine at low speed and in a small space. The raw physics dictate that in a fixed wing you'll arrive at 50mph or so.
The Robinson books quote a maximum glide ratio of 4:1 for the 22 and 4.7:1 for the 44. You're unlikely to be able to achieve this maximum from 1000ft though as it requires a particular combination of speed and rotor rpm which will take time and height to establish. I think from 1000ft you'd be lucky to get much more than half a mile. Your fixed wing would almost certainly travel further, but potentially do more damage when it arrived.
The river would be an option in the event of engine failure, which is why single engine commercial air transport work over the Thames requires floats.
Hope that helps.
The Robinson books quote a maximum glide ratio of 4:1 for the 22 and 4.7:1 for the 44. You're unlikely to be able to achieve this maximum from 1000ft though as it requires a particular combination of speed and rotor rpm which will take time and height to establish. I think from 1000ft you'd be lucky to get much more than half a mile. Your fixed wing would almost certainly travel further, but potentially do more damage when it arrived.
The river would be an option in the event of engine failure, which is why single engine commercial air transport work over the Thames requires floats.
Hope that helps.
Last edited by puntosaurus; 10th Jan 2013 at 09:52.
Taxi
Single engined helicopters have to follow the Heli Routes, which are strictly enforced by ATC. The routes are designed so that in the event of a failure, the pilot can always auto-rotate into an area big enough to land safeley - this includes the river Thames through central London. The lowest point on the Heli Routes is a short stretch over Kew (750' - to deconflict LHR traffic on finals for 27); the others are 1,000' or higher. I'd be very surprised if you saw many SE machines hovering at 1,000' on the Heli Routes.
Single engined helicopters have to follow the Heli Routes, which are strictly enforced by ATC. The routes are designed so that in the event of a failure, the pilot can always auto-rotate into an area big enough to land safeley - this includes the river Thames through central London. The lowest point on the Heli Routes is a short stretch over Kew (750' - to deconflict LHR traffic on finals for 27); the others are 1,000' or higher. I'd be very surprised if you saw many SE machines hovering at 1,000' on the Heli Routes.
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Thanks for the responses.
PuntoSaurus - that makes total sense.
toptobottom - now that you mention it the hovering is usually the turbines (noisy beasts
).
I live a stone's throw from Tower Bridge on the South bank of the Thames. As you say most of the singles seem to head eastbound curving north east, following the river. The views must be incredible. Sadly the closest I can get to it is as PAX flying into LCY (until I get my twin rating at least!).
London Bridge and Southwark are densely built up but I suppose the river is there as a failsafe option.
PuntoSaurus - that makes total sense.
toptobottom - now that you mention it the hovering is usually the turbines (noisy beasts
). I live a stone's throw from Tower Bridge on the South bank of the Thames. As you say most of the singles seem to head eastbound curving north east, following the river. The views must be incredible. Sadly the closest I can get to it is as PAX flying into LCY (until I get my twin rating at least!).
London Bridge and Southwark are densely built up but I suppose the river is there as a failsafe option.
Taxi
A turbine doesn't necessarily mean a twin, of course; most are SE and are therefore bound to stick to the Heli Routes. And a turbine doesn't necessarily mean noisier - an R44 makes a lot of noise compared to an EC120 for example (both prolific Heli Route vehicles).
You're not a NIMBY in disguise are you?!
A turbine doesn't necessarily mean a twin, of course; most are SE and are therefore bound to stick to the Heli Routes. And a turbine doesn't necessarily mean noisier - an R44 makes a lot of noise compared to an EC120 for example (both prolific Heli Route vehicles).
You're not a NIMBY in disguise are you?!
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Don't worry I'm definitely not a NIMBY!
As you would expect we get more than our fair share of aircraft noise by choosing to live as centrally as we do, but then we get more than our fair share of all sorts of other disturbances (drunks, tourists, traffic noise, obscene property prices
). But I live a five minute stroll from work which balances things out nicely.
You pays your money and you takes your choice, as they say!
Quite a few of the regular ones we see hovering are based at Redhill I think, with large camera pods on the front. Not sure of the type - Twin Squirrel?
As you would expect we get more than our fair share of aircraft noise by choosing to live as centrally as we do, but then we get more than our fair share of all sorts of other disturbances (drunks, tourists, traffic noise, obscene property prices
). But I live a five minute stroll from work which balances things out nicely.You pays your money and you takes your choice, as they say!
Quite a few of the regular ones we see hovering are based at Redhill I think, with large camera pods on the front. Not sure of the type - Twin Squirrel?
Toptobottom;
Sometimes we have to hover in the middle of a heliroute, and often do.
If a twin is hovering 'on task' in the middle of a heliroute then ATC will often close that heliroute to other traffic unless we can accept visual separation.
In a recent conversation I had with LAATC;
If the 'operating' traffic is within 1 mile of the heliroute that the 'transit' traffic is following then visual separation and thus passing is usually permitted. If it's beyond 1 mile from the heliroute then SVFR rules apply and 3 mile/1000ft spacing required so the route is made unavailable for transit.
But this doesn't mean you can wonder off the heliroutes by up to 1 mile and still be ok.
regards, MB
Sometimes we have to hover in the middle of a heliroute, and often do.
If a twin is hovering 'on task' in the middle of a heliroute then ATC will often close that heliroute to other traffic unless we can accept visual separation.
In a recent conversation I had with LAATC;
If the 'operating' traffic is within 1 mile of the heliroute that the 'transit' traffic is following then visual separation and thus passing is usually permitted. If it's beyond 1 mile from the heliroute then SVFR rules apply and 3 mile/1000ft spacing required so the route is made unavailable for transit.
But this doesn't mean you can wonder off the heliroutes by up to 1 mile and still be ok.
regards, MB
Thanks MB.
By an "operating twin that is 'on task'", do you mean police work? If so, isn't this is the exception rather than the rule; clearly it has priority over traffic that isn't on task, hence transiting traffic having to hold (in an orbit, not hovering!) or accept visual separation. Police may have to hover at a specific point in order to complete the task. For other commercial or private drivers, I can't think of a legitimate reason to have to hover on a heli route, especially in a single, even if on a film job?
On a slight aside, many moons ago I was hovering at Bedfont, waiting to cross Heathrow. Tower asked me to maintain a tight orbit instead as apparently I was invisible to radar in the hover (presumably primary, not secondary).
By an "operating twin that is 'on task'", do you mean police work? If so, isn't this is the exception rather than the rule; clearly it has priority over traffic that isn't on task, hence transiting traffic having to hold (in an orbit, not hovering!) or accept visual separation. Police may have to hover at a specific point in order to complete the task. For other commercial or private drivers, I can't think of a legitimate reason to have to hover on a heli route, especially in a single, even if on a film job?
On a slight aside, many moons ago I was hovering at Bedfont, waiting to cross Heathrow. Tower asked me to maintain a tight orbit instead as apparently I was invisible to radar in the hover (presumably primary, not secondary).
TTB;
I cant speak for singles operating commercially over London as I've only ever flown SEs on the heliroutes for transits.
Quite legitimate though for aircraft to hover for commercial reasons - both SE & ME -filming could be for a specific shot/location and the director may only want to do it from the hover.
Network Rail spend a lot of time in the hover and their railways criss cross the heliroutes.
Police have the highest category so take precedent.
In any case - all the operators filming/railways/news etc have to notify LAATC beforehand of their intended taskings as they aren't necessarily following the heliroutes. The heliroutes were designed for transiting the zone. I believe FlyingTV made a case for operating SE helis off heliroutes outside the specified area provided it was in locations where the could alight without endangering 3rd parties.
As for hovering versus orbits to hold - you are correct about being difficult to see on radar but also difficult to see you visually from the tower (the tower wants you visual before crossings). Orbiting introduces a movement which the naked eye can detect (hunter instinct).
Mode S makes radar's life a lot easier nowadays too.
I cant speak for singles operating commercially over London as I've only ever flown SEs on the heliroutes for transits.
Quite legitimate though for aircraft to hover for commercial reasons - both SE & ME -filming could be for a specific shot/location and the director may only want to do it from the hover.
Network Rail spend a lot of time in the hover and their railways criss cross the heliroutes.
Police have the highest category so take precedent.
In any case - all the operators filming/railways/news etc have to notify LAATC beforehand of their intended taskings as they aren't necessarily following the heliroutes. The heliroutes were designed for transiting the zone. I believe FlyingTV made a case for operating SE helis off heliroutes outside the specified area provided it was in locations where the could alight without endangering 3rd parties.
As for hovering versus orbits to hold - you are correct about being difficult to see on radar but also difficult to see you visually from the tower (the tower wants you visual before crossings). Orbiting introduces a movement which the naked eye can detect (hunter instinct).
Mode S makes radar's life a lot easier nowadays too.
Toptobottom - presumably you have not heard of the 'zero-doppler notch'? The reason you disappear from the Heathrow radar, when in the hover, is that it can't tell you from ground clutter because your radar return isn't modified by your speed in the hover (unless it picks up on the edge of your rotor disc).
Crab - hadn't heard of 'zero doppler notch', but I had worked out the physics. What I hadn't appreciated at the time (14 years ago) was that they use primary radar for the crossing - given the proximity, I'd assumed they relied on the MKI eyeball, at least until out of harm's way. Learn something new every day 
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"Network Rail spend a lot of time in the hover and their railways criss cross the heliroutes."
We hear plenty about flying cars but flying trains is another game all together....
Seriously, what do Network Rail do from the air with any kind of regularity ?
We hear plenty about flying cars but flying trains is another game all together....
Seriously, what do Network Rail do from the air with any kind of regularity ?
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The transport police machine would ook for metal theives, vandalisation, track incursions. i.e. typical police tasking (transport police).
Both Sky and BBC news AS355s based at Redhill.
Both Sky and BBC news AS355s based at Redhill.