High flyers

I just found this posting by a current A340 pilot on another forum. I thought I’d repost it here for interest.

‘The A340-300 does not fly lower than other airliners; in fact, it is usually a little higher – at least in the early part of a longhaul route. At M0.82, it flies a little slower than the B747 (M0.855), thanks to the less swept wing. The A340-600 shares most of the wing with the -300, but cruises a little faster (M0.83) – and will get to cruise altitude faster than either the A343 or the B744 at typical commercial weights. Neither A340 can cruise at the Boeings FL450 maximum, but their cruise maximum of FL410 is sufficient for most radiation-aware pilots.’

The implication from this is that the extra fuel the 744 has to carry due to being less efficient causes it to be unable to achieve more efficient levels until a later stage than the 340. In time however its performance will allow it to climb higher than the 340 if there is an advantage in so doing.

Most big companies will monitor a typical amount of mille-Sieverts of radiation a route will typically suffer at certain levels at certain times of the day and year. They will then ascertain from that a dosage that a typical individual will receive during a working year and in theory should ensure that it is not contravening recommended levels. Having said all that, the last time I saw any radiation charts they still had JMC written at the top!

Sky and wys.

Do you guys have some medical tests concerning those radiation levels?

Originally posted by Bmused55
More or less along the lines I thought.

The 747 from my understanding will cruise quite comfortably at .85 at various altitudes depending on payload.
Whereas, if I’m not mistaken, the A340 would struggle under the same circumstances.

So people, I guess the answer to this thread is fairly obvious.

For now, the 747 is the fastest cruiser.

BTW excellent thread. 5 stars!

Except that the original question was which airliner flies the highest…:rolleyes: – Nermal

Originally posted by skycruiser
Very true Ian, but the problem designing an aircraft like this is that it becomes too critical on its flight levels. If it can’t get its optimum level it doesn’t become that economical compared to other types.

More or less along the lines I thought.

The 747 from my understanding will cruise quite comfortably at .85 at various altitudes depending on payload.
Whereas, if I’m not mistaken, the A340 would struggle under the same circumstances.

So people, I guess the answer to this thread is fairly obvious.

For now, the 747 is the fastest cruiser.

BTW excellent thread. 5 stars!

Originally posted by wysiwyg
Sandy, Airbus went for efficiency over speed as they realised that the operating economics decide which type will be successful these days.

Very true Ian, but the problem designing an aircraft like this is that it becomes too critical on its flight levels. If it can’t get its optimum level it doesn’t become that economical compared to other types.

Originally posted by Jeanske_SN
The highest I’ve been is 37000 feet on a Dc10. Is it true a 744 is running at full power and is just able to keep .855 mach at 32.000 feet, and starts it descent at, say, 38.000 feet? That’s more efficient.

The 744 max alt is 45100 feet. I have had the 744 at FL374 doing .87 no problems at all, and no, it’s not on full power. The thing with the 400 is that there is little fuel penelty when you keep the speed up.

There is a lot of gold in the windscreen construction. This is one reason why they are 6 figure sums to replace. The gold carries out a lot of UV filtration.

What I’m getting at I suppose, is does being more exposed to the light make it more of a danger. You chaps don’t have the option of pulling down the blinds I’d imagine.

Are there any safeguards built into the glass, even if it’s extra ultra violet protection ?

Solar radiation leads to cataract problems, etc while cosmic radiation leads to increased cancer risks (if i remember correctly!). I believe it’s more the increased time of exposure we are susceptible to rather than being up front.

Does being at the sharp end make you more susceptible to solar radiation ? I’m assuming it’s more transmittable optically ?

Sorry, I’m mixing up my worms! Please substitute for solar!

Originally posted by wysiwyg
I’ll happily go to FL410 if lightweight at night (when there is little cosmic radiation) but prefer to stay below 370 during the day.

I thought that cosmic (as opposed to solar) radiation was constant, day and night?????

i have pics of the B741 that was operated by ABD at FL410 and m.86 on the gagues from my cockpit trips.

Sandy, Airbus went for efficiency over speed as they realised that the operating economics decide which type will be successful these days.

Re: Re: High flyers

As for Alt, concorde would normaly cruise between 50 and 55 thousand feet.

It was 60,000ft just thought i would give Concorde her glory.

Originally posted by skycruiser
The 744 I fly cruises at FL290 to 410. The plane climbs as the fuel is burned. Not many pilots like going above 400 due to the radiation. And the 744 is the quickest pax jet in the sky at the moment.

good ol 747 I thought it was still the quickest.
ever modern airlines like the A340 are slower than it, a fact that surprised me when I first found out.

I’ll happily go to FL410 if lightweight at night (when there is little cosmic radiation) but prefer to stay below 370 during the day.

The highest I’ve been is 37000 feet on a Dc10. Is it true a 744 is running at full power and is just able to keep .855 mach at 32.000 feet, and starts it descent at, say, 38.000 feet? That’s more efficient.

Max altitude for 757 is FL420 & for the 767 FL430, but you need to be pretty lightweight to get up there (like the first week in May, beginning of the charter summer season when many of the return sectors to the UK are empty).
As Skycruiser says, cosmic radiation is a real concern – it increases exponentially (I seem to recall) at the upper levels. As a passenger, it is probably of no great concern, but for flightcrew it certainly is. We spend our careers up there, and each generation of aircraft tends to fly higher than the last (zapping you with the invisible rays). Much of the evidence is, so far, anecdotal, but flightcrew are the guinea-pigs, and if it comes to a step climb further into the radioactive zone to save a couple of hundred kilos of fuel, forget it!