PPRuNe Forums - View Single Post - Dumping height; why not increase speed
View Single Post
Old 21st June 2004 | 10:01
  #7 (permalink)  
FlyingForFun

Why do it if it's not fun?
20 Anniversary
 
Joined: Jul 2001
Posts: 4,782
Likes: 12
From: Bournemouth
Whatunion, am I right in thinking that you're talking about being on the final approach to your field, and being a little too high? If that's the case, I don't believe that increasing speed would work.

If you think of the approach in terms of energy management, the situation you are describing would be a situation where you have too much energy. Increasing your speed will change that energy from height to speed.... but it won't reduce your total energy (at least, not significantly). You'll still have to get rid of the energy even after you've converted it from height to speed.

Compare this with sideslipping, which actually removes energy from the aircraft - a far more effective technique, since removing energy is exactly what you want to do. In fact, the idea of stalling, as suggested in the other thread, would probably be more successful in removing energy than your suggestion of increasing speed - assuming, of course, that you did manage to control the stall and land without spinning and crashing.


That's all true for the final approach, which, as I said, is what I think we are talking about. But if we are talking about being at altitude, then descending at high speed (in a steep descending turn) is exactly what I was taught to do for my CPL in the case of an engine fire, when the engine fire checklist failed to put the fire out. In this case, the steep descent serves two purposes. Firstly, it gets you close to the ground quicker - hopefully enabling you to land before the fire can take hold sufficiently to burn through something structural. Secondly, increasing the airspeed will aid in putting out the fire.

The technique I was taught for the CPL was to descend with full flap and gear down, at Vfe, with 45 degrees AOB, until the fire goes out. Then, wings level, gear up, flaps up, and commence a normal PFL.

However, on my Instructor skills test, my examiner suggested another method, which was to descend with no flaps, at Vne. The difference is that descending with full flap will give you a better rate of descent, and is preferable if you don't think the fire will go out. However, descending at Vne will obviously give a much higher airspeed, and therefore an increased probability of putting the fire out. So unless the fire has taken hold sufficiently that you don't think it can be put out by the airspeed, descending without flap at Vne may be preferable.

Your thoughts?

FFF
---------------
FlyingForFun is offline