[CORRECT AS IS] HUD falls away when landing

Hi everyone!

I've run into a recurring issue when landing the F-16 where the HUD will drop considerably when slowing to landing speed. Here's an example:

The image above is one of the more reasonable situations, however I have run into a few landings where the velocity circle and the bracket drop completely off the HUD as I'm reducing speed and setting the AoA. Coming from the F-18, it's very possible that I have some deep seeded habits that shouldn't be used in this plane when setting the plane up for proper AoA, but I'm basically doing the same thing as usual: Reduce speed to 250, lower the landing gear, extend the flaps, trim for nose-up attitude.

In most landings, the velocity circle is completely off the HUD (circle with X in it) as I cross the runway threshold but the AoA is correct just before it drops off the HUD. My friends who are flying the 16 have VR, and they say they just lift their head up to see the HUD data. In my situation without VR, my only option is to raise the seat significantly over the normal position. I saw Wags' video and noticed that his velocity circle and bracket were low, but just like with VR he's moved his head forward to see what's on the HUD.

Is there a way to correct this for those of us without head-moving stuff or are we just kinda out to lunch with this?

Your viewpoint is definitely too low and raising the seat is the correct thing to do.

Btw, you don't need to extend the flaps manually on the F-16 and you don't trim.

Looking at RW F-16 HUD videos, most pilots seem to fly the approach a tad faster, with the FPV aligned with the upper edge of the AoA bracket.

I'd rather fly the final a tad fast than a tad slow! https://youtu.be/5BJP7H52_YM?t=12

Your viewpoint is definitely too low and raising the seat is the correct thing to do.

I don't agree there because: (no zoom)

1: I have the same problem

2: If i raise the seat a bit the HUD image will go off of the top of the HUD.

Or should one be raising the seat before landing?

Your AoA is too high and the F-16 is landed opposite of the Hornet. Use pitch input from the stick to keep the flight path marker on the end of the runway and use throttle to maintain AoA (should be more like 11 degrees than the 13 you’ve got going in your screenshot, until flare anyway).

Edit: I should add that trim is just used to trim out whatever pressure you have on the stick to maintain your glide path/FPM position.

High AOA, basically your too slow.

If he really would have been too slow and the AoA too high, there wouldn't be a green AoA indexer light. With both indexer lights on, he's within limits.

...he's within limits.

But not optimal.

But not optimal.

And because the AoA is 1deg above optimum you should loose a part of the HUD (and sight of the runway)?

Btw, optimum AoA is 13deg. Fast at 11 and slow at 15.

I only fly in VR, so it’s a little hard to be sure from a 2D screenshot, but certainly looks to me like he’s sitting low.

I only fly in VR, so it’s a little hard to be sure from a 2D screenshot, but certainly looks to me like he’s sitting low.

Confirmed. If you compare it with real photos, from the correct seating position the pilot can easily see (at least) a part of the top from the glare panel and even the tip of the pitot.

https://www.airliners.net/photo/Singapore-Air-Force/Lockheed-Martin-F-16CJ-Fighting-Falcon/5662641/L?qsp=eJwtjDEOwkAMBP/iGgpAokgXCloo%2BIBlr0JE4E62JThF%2BTt3gW5nR5qZJL0Cn7iVDOrIwSZ32lBm46dTN9MD5Z1M66bzdneszpPFqVRWDvQiyAH9/xdTWFNwWTNDy%2B7bhF1/dGgRHT1PvFYQPE60LF/94i26

Confirmed? Not so much.

Two pics taken in succession 7 seconds apart, one with gear up, one with gear down. Look at position of gun cross and air speed. AOA indexer changed with gear down.

I’m not following. I don’t see what any of that has to do the position of his head/view.

Exactly. This is to show that it's *not* 'he's sitting too low'.

Exactly. This is to show that it's *not* 'he's sitting too low'.

? Don't know what you want to show or prove with your screenshots. Are you sure that the flap position is identical in both screenshots?

Are you kidding me? In the first pic (gear up) the g-indicator is at the '10'-mark of the ladder, in the second pic it is at the 5-mark (as in the OP's screenshot). The gun cross stayed at its position. Ergo, the g-indicator went down on the HUD with gear down.

That exactly is the point of the OP.

His viewpoint is no factor and neither is flap position.

That exactly is the point of the OP..

Nope. Suggest to re-read his first post. It's about this issue:

I have run into a few landings where the velocity circle and the bracket drop completely off the HUD

The boresight cross isn’t going to move...I’m still confused what you’re getting at and I think you may need to reread the OP.

Title of this thread:

HUD falls away when landing

Title of this thread: HUD falls away when landing

How about reading the whole post, not only the title?

Well, I guess it's up to the OP to clarify what he means

He’s not asking why his FPM is dropping, he’s asking why it’s out of his field of view at the very bottom of the HUD.

The F-18 has taught you some habits that don’t apply to the Viper.

Don’t trim for AoA on approach, just fly the FPM with the stick. Attain the right AoA using power, backwards from the Hornet.

Don’t fiddle with any flap switches, it’s not needed as they are all automatic with gear.

Fly the approach with the FPM at the top of the AoA staple (11deg AoA). When you flair pull and maintain a little power so the FPM drops to the middle of the staple (13degAoA). At touchdown it should be roughly at the bottom of the staple (15deg AoA).

If you’re still having problems scooch your seat up slightly to put the gun cross at the very top of the HUD.

There are a bunch of good HUD tapes of the F-16 that shows the landing.

Watch the last few mins of this to get an idea of how most Viper pilots fly AoA.

I tend to put the nose wheel down to early which makes the rolling start speed way to high. On short runways or if landed a bit to far on the runway it's often not possible to brake in time before the end of the runway.

Fly the approach with the FPM at the top of the AoA staple (11deg AoA). When you flair pull and maintain a little power so the FPM drops to the middle of the staple (13degAoA). At touchdown it should be roughly at the bottom of the staple (15deg AoA).

That does sound interesting, I'm going to try that, thanks! So far, I put the staple on the end (or rather beginning) of the runway and the FPM in the middle of the staple.