Delta Virtual Airlines Water Cooler

Delta Virtual Airlines Water Cooler | General Aviation Discussion | Optimal landings

DVA341
Senior Captain, B737-800

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Posted onPost created on January 04 2023 08:08 ET by Oren Geva

Looking at the optimal landing statistics, it seems that there is a strong weight to landing roll distance - as I see most top landings are in the 1250 ft ballpark, while their descent rate is around -250fpm.
The consensus around the internet though is that an optimal landing rate would be between -60 and -180 fpm - which will probably make the landing role a bit longer (as it will be a shallower landing, and perhaps faster).
Any thoughts?

Oren Geva

Senior Captain, B737-800

DVA388
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Posted onPost created on January 04 2023 09:39 ET by David Vega

Good topic Oren. It depends if one is flying a jet or a prop aircraft. There's a good source of info on optimal landings in the Pilot's Manual starting on page 27, sections "Hard Landings" followed by "Greased Landings." Airline pilots aim for safe over soft landings, but this doesn't mean hard, just hard enough to be safe.

Aiming for a soft landing on a jet does tend to make the landing roll longer. With ground effect and engines still spooling one could keep going for a good length when aiming for a greaser. When the runway is wet, one should aim to have the main wheels break through the water and make contact with the runway ASAP since braking can't be as aggressive as on a dry runway.

David Vega (DVA388)

Posted onPost created on January 04 2023 09:50 ET by Oren Geva

I understand that -300 is good, even if not super comfortable, -500 is hard - but acceptable, and that -50 is probably dangerous.
BTW - I ready somewhere that Boeings are built for -600. I am sure that number includes a safety margins, but maybe -800 is too hard?
But isn't the "Magic number" something like -150?
But if it is, then the rollout distance wouldn't be 1,250 ft. It's probably a bit subjective anyway, within reasonable limits.

Oren Geva

Senior Captain, B737-800

Posted onPost created on January 04 2023 10:09 ET by Oren Geva

Oh, I see I misinterpreted the distance parameter - it is the distance from the runway threshold, not landing roll distance.
So in that case I agree it's a very important measure for grading the landings.

Oren Geva

Senior Captain, B737-800

Posted onPost created on January 17 2023 16:50 ET by Oren Geva

So what is the formula? And where is the optimal landing distance?
Aiming at the aiming point usually means touching down a bit further, but it seems the sweet spot is at 1250?
And it also seems that the touchdown point outweighs the fpm by a LOT.

Oren Geva

Senior Captain, B737-800

DVA043
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Posted onPost created on January 18 2023 09:17 ET by Luke Kolin

The goal is to land 1,250 feet down the runway, at -250 ft/min. Vertical speed is weighted at 60%, runway distance at 40%.

Cheers!

Luke Kolin

Senior Captain, MD-11

Posted onPost created on January 18 2023 11:07 ET by Oren Geva

So 1250 ft at -250fpm is better than the same distance at -150fpm?
It seems nost VAs hold -150fpm as some kind of a holly grail number.
But it makes sense, because to aim for the aiming point and flare to -150 almost always gets me closer to 2000ft.

Oren Geva

Senior Captain, B737-800

DVA2887
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Posted onPost created on January 20 2023 10:30 ET by Andrew Vane

The thing on final is to get that aircraft on the ground. any finessing and you're increasing risk. At least this is what my CFI told me.

DVA used to have a greased landings list. This really isn't something to be proud of as most pilots would float it 2500 feet down the runway trying to hit -4 FPM. So, it was revised to a good safe, recommended target of 1250/250fpm.

Andrew Vane

Senior Captain, B727-200

Posted onPost created on January 20 2023 15:34 ET by Luke Kolin

FWIW I am attempting to calculate a better score than merely the average of two numbers. Unfortunately it involves math I haven't done since high school.

Cheers!

Luke Kolin

Senior Captain, MD-11

Posted onPost created on January 20 2023 19:27 ET by Andrew Vane

my engineering mind spinning. i will work on this...

Andrew Vane

Senior Captain, B727-200

Posted onPost created on January 21 2023 07:46 ET by Andrew Vane

Sent you an email Luke.

Andrew Vane

Senior Captain, B727-200

Posted onPost created on January 21 2023 12:02 ET by Oren Geva

Andrew Vane wrote:

The thing on final is to get that aircraft on the ground. any finessing and you're increasing risk. At least this is what my CFI told me.

DVA used to have a greased landings list. This really isn't something to be proud of as most pilots would float it 2500 feet down the runway trying to hit -4 FPM. So, it was revised to a good safe, recommended target of 1250/250fpm.

Yes, I don't know that 180 is a greaser necessarily, just stating my observations from elsewhere.
My understanding is that landing in the first third/touchdown zone is acceptable and safe. I don't know that there is a goal to touch down on the aiming point.
I find that when I am on a stabilized approach on the glideslope and touching down between 250 and 300 - my flare took me to around 1600ft.
So I was trying to aim to a bit before the aiming point - but that doesn't see safe either, so I ditched that effort.
Just now on the last flight I floated a bit too much, and touched down at -64 and 2200 - and being MEM where the runway was a bit shorted, I had to use some manual breaking early and overheated the brakes...

Oren Geva

Senior Captain, B737-800

DVA3390
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Posted onPost created on January 21 2023 12:47 ET by Lance Gomes

This is why this virtual airline is one of the best imho.
Almost all other VA's have a greaser list which is not what you want in an airliner.
I think I remember reading that a three-degree glideslope will intersect the runway at 1000 feet from the threshold.
Accounting for the flare, 1250 feet at 250 fpm sounds perfect to me.

Lance Gomes

Captain, DC-6

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Posted onPost created on January 21 2023 13:46 ET by Darrell Arview

Best goal, Dont break the landing gear, blow a tire, or throw your passengers into the seat in front of them, oh and do not run off the end of the runway. That will keep you from getting that dreaded message from ATC, that you need to call Joe after landing.

Darrell Arview (DVA13438)

Posted onPost created on January 23 2023 02:02 ET by Oren Geva

I am not disputing the rationale, but I am just wondering about the weights placed on the two parameters are correct.
For example, I have a -401fpm landing at 1278 ft ranked above a -253fpm landing at 1700ft.
Now - isn't a 400 a but on the hard side, while 1700 ft is perfectly acceptable and well within the touchdown zone?

Oren Geva

Senior Captain, B737-800

Posted onPost created on January 23 2023 09:40 ET by Luke Kolin

You're welcome to start a conversation with Operations. My changes over the last week has been to formalize the calculations. As far as I am concerned we can probably do different profiles per aircraft or even adjust based on runway length or weather conditions (I am not averse to loosening the tolerances based on winds).

Cheers!

Luke Kolin

Senior Captain, MD-11

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