Police Operators and low flying prohibitions

[Julian Hensey]

I am interested if police helicopter operators have any exemption from this rule in the UK - "An aircraft shall not be flown below such height as would enable it to make an emergency landing without causing danger to persons or property on the surface in the event of a power unit failure"

What defines power unit failure - is it one engine of two failing or a complete rotor power failure? or both?

[Droopy]

Perhaps the answer is in the "a" part of "a power unit...."
Which is one reason why there are no UK police singles.

[MINself]

Julian, any particular reason for this question, have you been irked by our friends in blue? and have you heard of Google?

http://www.caa.co.uk/docs/33/CAP612.PDF

Section 3, Chapter 3, Page 1 covers Police low flying.

What defines a power unit failure?

Mmmm.... an engine (power unit) deciding its had enough and opting out of the providing you power stakes! :rolleyes:

Singles cannot be used in the UK on Police Operations due to the location of the majority of Police Operations being over congested areas at low level.

MS

[Julian Hensey]

The question really came from seeing police helicopters a few hundred feet above major shopping centres, obviously probably looking for offenders in car parks having done a shoplift. I wonder how quickly, if at all, in the event of a major failure that they would be able to "be in a position so as to place the public in minimum danger."

[DBChopper]

obviously probably looking for offenders in car parks having done a shoplift

I'm inclined to think that when obviously and probably appear side by side in a sentence, then you have already realised just how unlikely that scenario is :rolleyes: . I work on a day to day basis in very close partnership with Air Support Units, and I can vouch for the the fact that shopping centres in general and shoplifters in particular take up very little of their daily work. Try: burglary / robbery / assault / firearms / wanted (for any of the above and more) / missing persons/ etc., etc...

That's not to say that a shoplifter (which can amount to anything from 50p's worth to thousands of pounds' worth) chased and lost by police might not result in an ASU search - of course it might - but that is probably the least likely of all the scenarios.

Ok, I know it wasn't necessarily the point of the thread, but you'll excuse me putting the record straight, Im sure :O

[thecontroller]

i can't see how twins are safer. still only one tail rotor, one main rotor, one fuel supply etc

http://www.youtube.com/watch?v=VjTpQJLm3xU

[What Limits]

Twins are not necessarily safer, but they do have independent fuel supplies, one to each engine.

The point is that the rule is to do with alighting clear in the event of a power unit failure. In a single, you are not as well off as in a twin.

In any helicopter, you are not well placed after a tail rotor failure, or a main rotor failure.

[Rushes]

Julian,

Even from a 'Few hundered feet' it is possible to fly away from a single power unit failure...... provided your at the appropriate weight!

R

[JimBall]

Even from a 'Few hundered feet' it is possible to fly away from a single power unit failure..

You can fly away - but do you honestly know where you will land ? Perf A or B?

Plainly that wasn't a question that crossed the mind of the pilot in the clip - and he didn't even lose an engine.

[Barndweller]

Jim.
To say that this question never crossed the mind of the Pilot in this clip is a tad unfair.
The Pilot was almost certainly acutley aware of his performance as most Police and EMS Pilots are. What he could not account for was the suddent and catastrophic technical / structural failure that ocurred. (he did however make a damn fine job of saving the crew - fortunately without serious injury to those on the ground).
Aeroplanes are vulnerable to catastrohic failure as well (although it could be argued less so than Helicopters). Just look at the A300(?) in New Jersey. Big Structural failure - crashed on town. We still see aeroplanes flying over cities don't we?

[Rotating Star]

Julian,
The chances are that the Police Helicopter you saw over a shopping centre at "a few hundred feet" was probably higher. If I'm engaged in a search I would normally aim to be at least 700' - 800' agl which gives a good compromise between seeing too much or being too low and drowning out ground patrols with the noise. At that height in the event of an engine failure there would be sufficient time to fly away and land somewhere safe.
RS

[Rushes]

Julian,


Performance is now classed as 1,2 or 3.

At classes 1 or 2 you are able to fly away from a single POWER unit failure, (T/R or other type of failure is a separate conversation), provided you are at the appropriate weight, speed, height configuration, which i'm sure the police ASU's would be for their ops.

Performance class 3, no hope, its down to terrafirma you go, and as JimBall says.... 'do you honsetly know where your going to land?'....., this is why police units and those operating in similar environments do so in twins.

Yes they still only have one T/R, but they have a little more redundancy built in in the power unit department, and thats a start.




R

[Helinut]

Julian,

Let me try and answer your questions straightforwardly, and with the minimum of jargon. The way that you have expressed your question hints at another agenda, but we shall see.......

Police operations are not exempt from the low flying rule that you quoted. However, they are exempt from other elements of the low flying rules. The PAOC/PAOM under which they operate substitutes lower limits for those other rules. In summary, the rules for police allow them to fly low enough to annoy people but not so low that they impose significant risk to people on the ground.

The CAA decide what risks are significant in writing their rules. They consider that the hazard to be protected against is the failure of an engine (a power unit). Since police operators want to a) fly at night and b) fly over built up areas they need to use a twin. So long as they operate at the right weight/mass the helicopter is designed and the rules require the helicopter to be able to fly away in the event of a single engine failure. The rules do not require the helicopter operator to be able to fly away in the event of other major failures:

e.g. double engine failure. main gearbox or main rotor failures or catastrophic tail rotor failures. The CAA (I assume) take the view that the risk of such events is so low that it is uneccesary to protect against these failures.

In general, these other failures are controlled by airworthiness design construction and maintenance measures.

To put the thing into perspective, cast your eye across the pond to the land of the free. The police there (generally) use much simpler single engine aircraft for the same role. They tend to fly lower but do more or less the same tasks. Occasionally, one of them has a power unit failure of its only engine. The helicopter inevitably descends (in autorotation) and the crew usually seem to find a place to land that causes the minimum of damage and danger to the public. Their Air Support costs a lot less than the equivalent in the UK, so we UK tax payers pay a price for the higher standards the CAA impose on UK police operators.

[Thomas coupling]

I wouldn't wish to comment on the US failure rate Vs ours.

However, consider this:

Problems can and will develop in the
Fuel control unit
Governor
Oil pressure system
FODding of an engine

In fact any ancillary aspect of an engine can develop a fault and indirectly be the cause of that engine failing to operate properly. It isn't as most people would expect: an engine failure perse.

But the consequence of any of these accessories failing (of which there are several) can have a massive effect on the outcome if there is only ONE engine on board!

Two engines provides significant redundancy for which I am eternally grateful!

[FairWeatherFlyer]

If I'm engaged in a search I would normally aim to be at least 700' - 800' agl
Is that for visual purposes or due to limitations on the stabilisation platform for the camera?

From a noise point of view, it would be nice if the police squirrels over london were a bit higher at times. Are they compressed in by the air space + activity above them?

[Helinut]

FWF,

All helicopters within the Control zones around London get forced down by ATC clearances. It gets worse the closer you go to the final approach after take-off tracks.

[Rotating Star]

FWF,
If you are too high on a suspect search you can miss out on the detail and the camera won't be as effective, and if you are too low it can compromise the search especially in an urban environment where because of the angle of view, suspects, vehicles etc. become hidden behind buildings, walls and anything in line of sight. However if something has been spotted that requires further investigation then I might be asked by the observers to lose some height. Getting a better view under a bridge or a vehicle can be achieved by descending 200 - 300'.
Cameras mounted on Police Helicopters are gyro-stabalised so height has no effect on image quality, although the aircraft will be affected to some degree by turbulence from obstacles on the ground if the wind is strong enough.
If you think Twin Squirrels are noisy, wait till the Met are up and running with their EC145's!!
RS

[Hoveronly]

I left UK Police work some years ago and at the time (if memory serves me well) ASU aircraft were not allowed any special dispensation from the CAA. Indeed, we all had to know the regs in order to later justify breaking them if need be. 500ft was about ideal over a shopping centre when using the loudspeakers to ask shoppers to look for a small child who was missing. Through out that operation the pilot would have been acutely aware of his single engine climbout perf. Obviously the higher the better when pucker factor kicks in!

[jayteeto]

You can fly away - but do you honestly know where you will land ? Perf A or B?

Yes you do honestly know where you will land. You fly on the other engine to your chosen landing site, then land. Most days you can even hover taxi on one engine if you need to. If you really have a problem with 'catastrophic failures' over a city, lets shut heathrow, glasgow, birmingham etc etc for big jets. In fact, lets ban flying altogether, just in case a jet crashes. Following on, how many police helicopters have had these major tail rotor failures and crashed in the city, killing loads of people. Compare that to say.... cars.... or coaches..... or motorbikes..... or trains.... or horses...... or pushbikes..... or pogo sticks. All have killed as many people as helicopters, so we should ban them from towns and cities. Roller skates.... ladders..... stairs...... lawnmowers...... electric drills....... screwdrivers....... all killed more people than helicopters. Get the idea????
PS. I am mad.

[AlanM]

The 145s have been at Southend and Biggin trg - and have had lots of complaints.

Wait til Red Ken gets them over London Bridge at 800ft!

[Helinut]

I am told the training is going to go on for several more months yet!

[AlanM]

Cool. Sounds like the boys are having fun with the new kit. They say things like "Got him on TCAS" now....!! :)

[sss]

Got him on TCAS

tell him to look out the window like the old days, :uhoh:

[ShyTorque]

No police pilot looks out of the window these days, it's so - well, you know, old fashioned. :hmm:

He'll be hovering fully on instruments, of course. All one has to do is watch the TCAS and at the last second, just pull up or fly down to avoid the huge disaster over London. S'easy. :cool:

Strewth!

P.S. Anyone else think 145s look like those big, ugly, bumble bees? 'Specially painted in their bumble bee colours. They certainly sound like them. ;)

[AlanM]

To be fair to them they were IR trg at the time......! :ok:

(Hey ShyTorque - you owe me a beer for every time you say "got him on TCAS!!!")

tee hee

[ShyTorque]

I would do but I got no TCAS these days - I just pretend I've got one and look out the window and then in at the clock to see how long I've been holding outside the zone :p

(actually it's called TAS on these new-fangled sportscars but that don't sound right on the radio ;) )

[JimBall]

then in at the clock to see how long I've been holding outside the zone :p

And last Saturday afternoon all the normal traffic was looking at its calendars whilst 2 police helis claimed the zone near Heathrow for an "indeterminate" time. That made getting racegoers to Sandown a slow task.

But just who was the pilot who lost his temper with the delay and told the controller he had a sick pax onboard ? Then, when asked if he wanted to declare an emergency, said no.

Come on, chap, they're either throwing their stomach over your epaulettes, or they're not. Didn't you do the "bad excuse call" training ? ;)

[AlanM]

Aww bless 'em!!!

OH well - when the LCTR goes Class C we will all be happier.

[JimBall]

OH well - when the LCTR goes Class C we will all be happier.

and a lot older.

[semirigid rotor]

Didn't I read somewhere recently that LAPD have just won an award for something like 35,000 hours of safe flying? All in singles over Los Angeles. Great achievement guys and girls, well done:D