6300 ft To Cross 19 miles of Water????

[Monocock]

This is not meant to be nit-picking topic but I have been thinking about this ever since I heard it this afternoon.

Returning from Cherbourg and communicating with London Info I heard a C150 pilot announce that he was "mid-channel between Calais and Dover at 6300 ft !!!!!!!!".

Is that a perfectly calculated height for guaranteed glide with an engine failure?!!

Surely the poor little 150 must have taken an age to get up there putting for more stress on its Continental than a quick run across at 3000ft.

[Whirlybird]

Well, I don't know exactly, but...

6300 feet, with about 10 miles to run, is about the same as 600 ft with a mile to run, ie normal height on short final. So it sounds to me like he definitely could glide to land with engine failure. And he could have cruise climbed to that height while over land, which wouldn't be too much of a problem or stress on the engine.

Hmmm, on reflection, I think I'd do it that way myself, assuming a nice clear day so you can get the height without running into cloud - or assuming I get an IMC some day. Sounds sensible to me, now I come to think about it.

[rustle]

The only unsensible thing about this is that at Alt6300 even with a QNH of 1013 he/she is 200' under CAS.

Today's QNH may have put him/her inside the Class A at that altitude if he was "mid channel between Calais and Dover at 6300 feet". (Worthing CTA starts at FL65)

What was the QNH in that area?

Edit: Answering my own question... EGLL currently giving 1040, so he was in CAS at that altitude - which may be why they (London FIS) asked ;) [unless it has leapt 20+ millibars since this afternoon]

[Keef]

I'm with him! I usually cross at FL55 going to France and FL45 coming home. There's a bit in the middle where an engine failure would mean I get wet, but I don't tell the aeroplane about that.

If this pilot was at 6300 feet, shouldn't he have been on 1013.2 anyway?

[bookworm]

Any chance you're winding up instead of winding down there rustle? I have to think about it hard every time and I'm still not convinced I get it right, but I would have thought 6300 on 1040 is more like FL55.

[Keef]

"High to low, look out below."

QNH falls, you don't adjust, you bang into hills you thought you would miss.

Set 1013 when it's 1040, you're a lot higher than the altimeter says you are.

Yon C150 isn't in controlled airspace. I wonder how long it took him to get up there, though.

[rustle]

:O

bookworm/keef

Oops. :O

Think I'll stick to gags about B767s :)

The prosecution has now retired, hurt...

[5150]

I came across the same stretch last monday from Lille to Coventry. I seriously doubt that it was calculated exactly - they were probably at FL63 just to avoid the airspace above which starts at FL65. Yes, it does take a while to get there in a small aircraft, but you get the gliding distance, air is smoother and it's more economical.

[Avoiding Action]

Setting aside the issue of CAS above, I honestly don't think you can ever get high enough over large bodies of water with a single engine. Recently flew from Inverness to Shetland and took the 152 up to FL110. It took an age to get up there, but it made me feel so much more comfortable;) Naturally it was a pure VFR day :cool: and I had great fun watching the Loganair SaaB 340 flying south underneath me. You definately wouldn't have caught me 'doing a quick dash at 3000 feet' over 25nm or so of the North Sea / North Atlantic:eek:

AA

[Barney_Gumble]

I guess it depends on the glide performance of the a/c. If you calculate based on 6082ft in a nm and use an average still air glide range of 9:1. Then for 9.5 nm (57779ft) (worst case mid channel engine failure) a good start point would be 6420ft.

Next thing would be to take account of headwind or tailwind e.g. gliding into headwind will reduced the glide range and tail wind increase it.

Lastly take into account Quadrantal rule and any controlled airspace and make allowances for not new a/c and flight technique not that of test pilot.

I tend to think, fly as high as possible giving the engine a little breather periodically by lowering the nose on the climb to get some faster flowing air over the engine to cool. Also helps to check ahead for any conflicting a/c.

6300ft does seem high in practice though. I would just take middle road of risk reduction by flying at FL55 and FL45. Then just ask Keef to have a word with the boss upstairs during the minute or so of feet wetting potential in the middle :eek:

Barney

[A and C]

Please can you tell me why the engine on this aircraft would suffer more stress in the climb from 3000 ft to 6300ft than it did in the climb to 3000 ft ?

[bookworm]

A and C

I can think of three factors:

1) Vy reduces with altitude, hence so does cooling at Vy.

2) Whereas the lower part of the climb can be flown at higher than Vy for better cooling without dropping below an acceptable rate of climb, at higher levels the speed needs to be pretty close to Vy to maintain a decent rate

3) It takes much longer because the rate of climb is lower

Mitigating that is the fact that the engine is putting out less power, hence less heat needs to be dissipated.

[Final 3 Greens]

Just a point. If you have to glide from mid-channel, you don't just need to allow for a glide to the beach, there is also a need to have some manouvering space left over the beach, to pick a decent spot.

[greatorex]

Maybe he also wanted to climb above this damned haze that seems to be a permanent feature here in the South East at the moment?!?

I took a few friends for a flight across the drink in a chum's plane on Saturday and the viz was awful up to 5000ft after which it became as clear as a bell. Call me old fashioned, but when I fly privately, I like to be able to see what I may be bumping into up there. . . . :) ;) :) ;)

[A and C]

I wondered what answers I would get to my post , with such a consice answer you have rather spoilt my fun !.

[bookworm]

Sorry A and C :)

I certainly see what you're driving at. I can see no reason why it should be particularly difficult to get a C152 to 6300 ft. That said, with rather better performing aircraft (but still SEP), I have found that it's the latter stages of the climb to cruising altitude that are more difficult to manage than the earlier stages.

[alphaalpha]

Flying high across the Channel or any biggish stretch of water always seemed to me to be a good idea for three reasons:

a) Gliding range, as discussed already on this thread

b) Less traffic higher up. There is a fair bit of VFR traffic between Dover and Cap Gris Nez at 3000 ft on a VFR day -- in both directions -- and its particularly hard to focus for effective look out when the weather's hazy.

c) Flying quadrantal or semi-circular rule higher up further reduces the risk of collision.

Taking reason b) further, flying from France to the Cambridge area, I like to fly just under the 4500 ft LTMA base to the east of Stansted zone because there seems to be much less traffic here than at 2000-3000 ft further west. Especially worth while on a good VFR day (like last week-end) when there are lots of people flying and such radar service as is available is limited by traffic and controller workload.

AA.

[KitKatPacificuk]

Less traffic higher up!!!

If you ask me there's less traffic at 1000ft or below over the Channel!! More fun too!

Remember your engine doesn't know it's over water!

[Monocock]

I sort of see your point but if the engine did decide to go "breasts up", you 'aint got long to talk to London Info/121.5 before you're talking to the fish.....

[Leclairage]

KitKat I am sure this is exhilerating...would enjoy trying this myself....but not sure you should be encouraging others to do it.....as pointed out in the last post there aint much time to get help organised.

[FlyingForFun]

Monocock/Leclairage,

Lighten up! If KitKat wants to fly across the Channel at 1000', that's up to him. He's certainly not going to crash into me if he's unlucky enough to have an engine die while he's down there!

Ok, seriously, there is very little risk to anyone except you if you choose to do this. I'm sure it's good fun, and most things which are fun have an element of risk with them. As long as you're not putting others at risk, it's entirely up to the individual to decide whether the extra risk is justified by the extra fun.

FFF
-------------

[Gerund]

I reckon KitKat has the right idea; only thing I disagree with is that the engine DOES know it's above water and has a bit of fun.

Gliding to land can be a bit academic though if you're not given the option to climb. I remember flying back from Jersey to Compton Abbas (and the Channel is quite wide there!!) and being cleared out of the Class A airspace, special VFR, at "not above 1,500ft".

Anyway we are only talking about the channel after all................single engine craft routinely fly across the Atlantic.:D

[englishal]

If KitKat wants to fly across the Channel at 1000', that's up to him
In fact I have been told by Jersey "Not above 1000" which gave me a bit of a twitchy rpiece :D

My general rule I use is to continue climbing until I get to a point where I can start a 500 fpm decent all the way to the detination, unless restricted by airspace, or hideously high altitude. If I'm crossing a long stretch in a SEP I'd go up to 12,000ish if I was allowed, or if not, the highest possible altitude available. Altitude = insurance in my book......

Cheers
EA:D