777 with cargo/cabin fire. How would you handle the high speed approach to get on the ground ASAP?
I think the major variable in a uncontrolled cargo/cabin fire is not how fast you fly the latter stages of the approach but how far from a runway you are when you first diagnose the issue. Coming in with so much energy that a runway excursion is a serious possibility if you don’t throw the approach away seems counter productive.
The 777 is a long range aircraft much used on EROPS over sparsely populated and/or inhospitable environments. It is most likely that you’ll be in a position where serious consideration will have to be given to an off-airport landing or ditching (“controlled crash”).
If you do decide to go for an airport vs. putting it down on whatever’s underneath, the major attractions are a) the chance of coming to a halt on a paved surface without damaging the airframe and generating additional problems plus b) having fire/emergency services that are specifically equipped and trained to deal with aircraft.
That’s not to say a highly expeditious approach is a bad thing but if puts you in a situation where you’re on fire and have a choice of a high-speed overrun into ugly terrain or spending quite a few more precious minutes having another go, then you’d have been better off coming in a bit slower and making sure of it.
If you really want some numbers for a standard ILS, I wouldn’t like to have a GS > 200kts going through 1,000RA. Bear in mind that that it is likely you will be over MLW, possibly by a long way, so it’ll be more difficult to slow down than normal. As you’re going for the nearest bit of tarmac, there may be an adverse wind component as well. At normal landing weights you can lose about 20kts per mile with speedbrake in level flight, more with taking the gear early. If you did what you do normally only 1,000’ lower, it would likely be a good compromise...