Turns when initiating an emergency descent depends upon environment; On an isolated airway it can make sense. Overhead London you are just compounding your problems. We have it from LATCC that they would prefer us to stay on any assigned heading unless we have someone directly below us and MUST turn to avoid them.
As A37575 says, there is no justification for deliberately overbanking into an unusual attitude to get the descent going quicker...no need whatsoever.
The most important things to do are the recall items in your QRH and then to initiate the descent if required. Once the descent is underway a very good idea is to sqwark 7700 (that came from our LATCC liason sessions too) as you light up like a disco light on the ATC screen and they will immediately start getting other aircraft out of your way (easier for them to do if you stay on your heading). This has the added benefit of flagging you up to other sectors (possibly below) whom you are not in two way comms with. They too would be initiating help on your behalf. Remember, communication with your colleague and ATC can be quite difficult with that damned oxy mask on!
Turning on the runway in the event of a fire. Well, the theory sounds good, but in practice, in the real world when RTO has kicked in you will pull up extremely briskly. 'Consider wind direction' is just that. It doesn't mean that Boeing are telling you to make a turn before you come to a standstill. My opinion is that you are potentially wasting time by looking for this suitable taxyway to turn onto or trying to position a big aircraft across the runway. Other relevant points have already been stated such as access for fire vehicles and crews, pavement strength issues etc.
It is interesting that the Manchester 737 fire incident has been quoted. They executed a stop for a perceived burst tyre or birdstrike from 125kts. The commander told the F/O 'not to hammer the brakes', so they didn't stop as quickly as they could have. They also 'intended to clear the runway to the right'. Again, more seconds whilst still moving. 'Reverse was cancelled at 70kts' and the aircraft took '45 seconds to stop'. In my book that is quite a long time for an RTO. They had some unlucky breaks in that the wing had ruptured and fire spread quickly, the R1 door wouldn't open until 1 minute and 10 seconds after the aircraft had stopped.
They were on runway 24 with a wind of 250/7. They turned onto the Dalta link in an attempt to clear the runway, with an uncontained fire in the left engine/ wing. The last survivor, a young boy, was pulled from the overwing exit by a firefighter some 5 minutes and 30 seconds after the aircraft stopped. Time was of the essence in this incident. 55 lost their lives.
Hindsight is a wonderful thing.
Several recommendations were made, including;
1. Procedures should be developed to enable the crew to position an aircraft , when ground fire emergency exists, with the fire downwind of the fuselage.
Good idea, but non of the four airlines I have flown for have any such procedures. They assessed and decided that stopping straight ahead as quickly as possible on the runway was more suitable.
2. Research should be undertaken into methods of providing the flight deck crew with an external view of the aircraft, enabling them to assess the nature and extent of external damage and fires.
Again, good idea and easy these days, but I haven't flown a type with such a facility.
3. Operators such amend their Ops Manuals, if necesary, to direct crews on any rejected take-off or emergency landing to stop on the runway and review the situation before a decision on clearing the runway is made.
Always do this one.
Many other recommendations too, including;
4. Onboard water spray/ mist fire extinguishing systems having the capability of operating both from on-board water and from tender-fed water should be developed as a matter of urgency and introduced at the earliest opportunity on all commercial passenger carrying aircraft.
Yeah right.
So overall, I reckon pulling up expeditiously on the runway, straight ahead, and carrying out the correct drills promptly, initiating the evacuation promptly when required is the best option....just my opinion though.
PP