Descent rate final approach

[SkilledMusician]

Hi,

I'm an enthusiast and use an ipad flight sim app called infinite flight. I have a question about descent rates. I am aware that a descent rate of about 750 fpm is average for following the glide slope. Do pilots decrease the descent rate when passing over the threshold at 50ft? The flight sim app I use has uses a HUD as it's main interface which allows me to follow the ILS all the way touch down, except for the flare obviously, which I begin at 20ft on a 737.

However, I notice that when continuing precisely on the glide slope after passing the threshold, the altitude callouts 50,40,30,20 seem faster than what I hear when observing cockpit videos on YouTube.

I also saw a video of a 737NG landing with a HUD, and noticed that the pilot eased the descent rate to about 600fpm when passing over the threshold.

Can anyone confirm what is the right thing to do?

[SkilledMusician]

Note: This is using a 737 flying 155 knots jus under max landing weight.

[glendalegoon]

hi


first off, if you multiply 5 times groundspeed in knots you have the foot per minute rate of descent to maintain a standard 3 degree glideslope.

we do reduce rate of descent near the runway, we call it the FLARE.

touching down at 750 fpm would be a very hard landing.

500fpm is ok for wet or short runways but is firm

300 fpm is usually pretty nice and the max for an overweight landing.

so, where do you start the flare? that's a secret that takes years of flying to really understand.


or there is some advice on flares based on when the fixed distance markers go under your nose.

but I think you should take half your wingspan and use that as the height above touchdown to reduce your rate of descent.

have a nice day.

OH, what instrument do you play skilled musician?

[SkilledMusician]

Thank you for your response GG.

I'm definitely in agreement with not touching down at 750fpm and am aware of flaring. My question was about whether there is any slight pitching up whilst passing the threshold.

What you said about ground speed was interesting. My ground speed was about 160kts. This gave me a descent rate of 800fpm. I was watching my descent rate whilst following the glide slope indicator and it was between 800 and 850, which was why the altitude call outs were too fast. After lowering my ground speed to 150 kts, the call outs sounded more normal.

My reasoning for flying at 155kts airspeed (160 ground speed) was that I was under the impression a b737-8 at max landing weight would have an approach speed of 155kts (airspeed) vref + 5kts.

[SkilledMusician]

Oh, and I play the piano.

[DaveReidUK]

My reasoning for flying at 155kts airspeed (160 ground speed)

Don't try landing your sim with much more than that 5kt tailwind ...

[SkilledMusician]

I have zero wind set at the moment on the app. Perhaps this is an app design fault? Should airspeed = ground speed with no wind?

[student88]

No, ideally you'll continue with constant rod until the flare.

[SkilledMusician]

Thank you student.

[JEM60]

Whilst descent rates on Flitesim are being discussed, a question from my flightsimming neighbour. Is more than 2,000fpm considered excessive on a normal descent from a level, at say, Mach.7 with 33,000 feet to lose, and 100 DME to destination. Would more be considered comfortable for pax, and what would be considered highest normal allowable rate of descent [from pax point of view, rather than ATC requests] Ta muchly.

[carbheatout]

5 x table is far too complicated for my brain on the approach. I half the GS and add a zero. So, doing 200 knots you need 1,000fpm.

[+TSRA]

Passengers won't notice the descent in fpm (aircraft that is). You could do 1,500; 2,000; 4,000 fpm - most won't notice. There are, of course, extremes to this, but I'll work around the 2,000 to 3,000 mark.

What they will notice is the deck angle, or nose down attitude of the aircraft. Anything more than about 7 degrees nose down starts to get a little uncomfortable for some people, not to mention it becomes harder for the flight attendants to walk up and down the aisle.

Furthermore, it depends on whether the aircraft pressurization system can keep up. For some airplanes I've flown, a 2,000 fpm descent meant catching the cabin around 8,000 feet no matter what I did to the computer. On others you could go up to 3,500 fpm without having to worry about it. I don't usually let the cabin get above 700 fpm as I've found any higher generates one or two comments.