Two engines over the Pond??

[watchingbrief2000]

Can anybody out there answer me this?
I recently flew fom the USA to UK on a Boeing 747 400. The aeroplane was only about half full with us SLF. I would swear that I could only see contrails emerging from the inner engines, i.e numbers 2 and 3. Is it permissable to shut down the other two engines, whilst at cruise? As well as being lightly loaded our speed was lower than usual.:confused:

WB2K

[MacBoero]

The contrails are not visible immediately on exiting the back of the engine. There is a finite amount of time for the water vapour in the exhaust gasses to condense and become visible. As the inner engines are further forward, you are more likely to see them. You may not have been looking back far enough to see the contrails from the outer engines.

Well, that's my guess anyway! :)

[Rainboe]

Correct. B747s don't shut down engines to conserve fuel! A very slightly lower cruise speed would automatically be selected by the flight management system for economy reasons due to lighter weight, but frankly 150 people would still only weight 15 tonnes or so which makes virtually no difference. A minor reduced speed may have been given by ATC across the Atlantic, but apart from that, cruise would have been very approximately Mach.84.

[13 please]

Rainboe, thanks for that, as cabin crew who's been on the 747 for 14 years now, I've been holding my breath waiting for someone like you to answer..!!

PHEW..!!

[GroundedSLF]

Rainboe - thats a bit of a guess on the weight of 150 pax isnt it? especially as it was USA to UK...

I would of thought that 150 "average" American citizens would easily equate to 250 tonnes - each:E

[watchingbrief2000]

Thanks for all the replies, folks.:)

[Avman]

Then again, if it was BA.........................? :E ( ;) only kidding)

[radeng]

One engine was good enough for Lindbergh: two were fine for Alcock and Brown....Plenty of Liberators flew over, and they only have two!

On a more serious note, is it true that the reliability of ETOPS has far exceeded the predictions at the time it was introduced?

[Skylion]

1) Liberators=4 engines.
2) On most N Atlantic tracks you are not far from land. Not very hospitable land but land nonetheless. Some mid and South Pacific routings have less solid stuff nearby.

[Rainboe]

Try looking at 51-53 degrees North, 30 degrees West and see how near to land you are! I think Atlantis has sunk now- there ain't no land near there!

[Pugilistic Animus]

Is it permissable to shut down the other two engines, whilst at cruise?

only for loitering on certain military flights,...AFAIK,...I'm not military

*on the A340 it's also permissible,...because the pilots get sick and tired of all that useless droning:}:}:}

*just a joke

[Tolsti]

Alcock and Brown????.... I thought it was Sammy Davis Jnr!!

[BladePilot]

Didn't Sir Richard do it without engines?