Ryanair 738's T/O distance req.

[Caledonian]

Hi,

Been discussing with some other folks on another site re the 738 of ryanair, some peeps reckon this aeroplane needs at least 6000 ft of runway to operate from and a runway like aberdeen's for example is no use for the 738 because of the engines it has fitted???? I find this very strange as we all know that the 732 wont be around forever and surely the 738 would need to be able to operate into somewhere like Aberdeen??

Any ryanair drivers out there care to comment so that this discussion can be settled?!

Cheers

Good Luck to ya

[Localiser Green]

I know Britannia's 738s were not much use at EGNM (Leeds) on the longer flights for the Summer they were based there (2000?). Couldn't do the longer Canary Islands / Cyprus runs without a stop (while Airtours A321s / A320s made the flights non-stop).

BY now use the B752 at Leeds again.

The 737NG is great in that with the new wing it can now cruise at M0.78 like other aircraft of its size (320 / 757) but like everything in aviation if you get a plus somewhere there is a minus somewhere else. Faster t/o and ldg differences seem to the the minus.

In terms of what runway length is needed remember that the ASDA (Accelerate-Stop Distance Available) and TODA (Takeoff Distance Available) are more important factors in performance terms than the actual length of the paved surface.

[OverRun]

Caledonian,

The difference between the 732 and the 738 is substantial. The size and capacity are quite different - the empty weight of the 738 is some 14 tonnes heavier than the 732 for example, so even an empty flight is a lot heavier in the 738.

One of the stories about the 738 is that it is more like an early model 707. The 79 tonne MTOW HGW version carries 155-189 pax and max payload range to 2940 nm. The 707-120 was 110-179 pax mixed class seating and max payload range to 3300 nm. So to put a perspective on your question, it is almost like asking will a 707 fit into 6000' of runway? The answer is 'with difficulty'.

For the case for the 737-800, 2000m runway, sea level, standard day, wet runway (hey - wet runway has to be a standard day in Aberdeen):
CFM56-7B24 ENGINES AT 24,200 LB SLST = 69.5 tonnes takeoff weight
CFM56-7B26 ENGINES AT 26,300 LB SLST = 74 tonnes
CFM56-7B24 ENGINES AT 27,300 LB SLST = 75.5 tonnes

Given that discount airlines often lease planes with the smallest engines, or derate larger engines in service to reduce the maintenance requirements, it is possible that the engines are being run at 24,200lb. This would make it a bit tight on 2000m, with a reduced load capacity, depending on the length of sector.

It's not going to be easy to settle the discussion without quite a bit of analysis. I guess that's why we need performance engineers :D