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Greased Landings = UNSAFE...


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Can someone please explain to me why 'greased landings' have become popular and seemingly encouraged on VACentral and the associated stats/scores?

Greased landings are UNSAFE and surely should not be encouraged due to the amount of runway used/needed and the possibility of ending up through the nearest fast food restaurants plate glass windows should a gust of wind choose to hit the aircraft?

Tim Walters

MaldAir.com / EurOzone.com / MAlitary.org / EUSART.org

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I have done some research on this and it seems that the subject can be hotly contested at times, your bold enlarged text reinforces that, and forgive me as I am more of a coder than a pilot.

What I have found so far is that aircraft manufacturers do not have, that I can find as yet, a minimum recommended rate of decent at touchdown. I think days could be spent reading both technical and emotional posts in various forums and manufacturer sites.

The one solid piece of information I have found is the design criteria for aircraft landings put out by the FAA. It states:

Overweight landings are safe because of the conservatism required in the design of transport category airplanes by FAR Part 25.

A sink rate of 10 feet per second at the maximum design landing weight and a sink rate of 6 feet per second at the maximum design takeoff weight.

The FAA in the same design considerations continue with this paragraph;

Typical sink rates at touchdown are on the order of 2 to 3 feet per second, and even a “hard” landing rarely exceeds 6 feet per second. Additionally, the landing loads are based on the worst possible landing attitudes resulting in high loading on individual gear. The 747-400 provides an excellent example. The 747-400 body gear, which are the most aft main gear, are designed to a 12-degree nose-up body attitude condition. In essence, the body gear can absorb the entire landing load. The wing gear criteria are similarly stringent: 8 degrees roll at 0 degrees pitch. Other models are also capable of landing at maximum design takeoff weight, even in unfavorable attitudes at sink rates up to 6 feet per second. This is amply demonstrated during certification testing, when many landings are performed within 1 percent of maximum design takeoff weight.

I refer to the first sentence stating “Typical sink rates at touchdown are on the order of 2 to 3 feet per second, and even a “hard” landing rarely exceeds 6 feet per second”. Using their “Typical” touchdown rate as a guide to a good landing, or typical landing rate would be between 120 ft/min and 180 ft/min. Many sources state that anything as low as 50-80 ft/min are acceptable depending on flight conditions, and of course there are the simulator forums with the argument that -1 ft/min is the best rate possible. By design standards, anything over 360 ft/min at maximum design takeoff weight and anything over 600 ft/min at maximum design landing weight would be considered a “hard” landing requiring inspection of the aircraft.

The question becomes how to apply a value to a landing rate and what is acceptable.

1 - Do I penalize anything less than 120 ft/min and anything over 600 ft/min?

2 - How do I apply a value to the landings between 120 and 180 which are considered “typical” by the FAA?

3 – What is the lowest acceptable landing rate without the landing being considered “unsafe” and a higher penalty being assessed?

4 – Do I penalize a va not submitting landing rates?

5 - This FAA information is for transport category aircraft, do I apply different parameters to GA?

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1 - Do I penalize anything less than 120 ft/min and anything over 600 ft/min?

2 - How do I apply a value to the landings between 120 and 180 which are considered “typical†by the FAA?

3 – What is the lowest acceptable landing rate without the landing being considered “unsafe†and a higher penalty being assessed?

4 – Do I penalize a va not submitting landing rates?

5 - This FAA information is for transport category aircraft, do I apply different parameters to GA?

Good Points ;)

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This is just my opinion - do take it with a pinch of salt as I too am more of a coder than a pilot:

Point 1: I would certainly penalize anything under 50fpm as the pilot appears to be deliberately trying to achieve the lowest landing rate rather than landing on the touchdown zone with plenty of runway ahead.

Our flight tracker automatically rejects reports with landing rates above 700fpm and anything between -600fpm and -700fpm have to be manually approved. The remainder are automatically accepted at time of filing, assuming no other parameters are exceeded (pitch, bank etc.)

Plan 'B' for point 1: Penalize airlines that accept landing rates above 'xxx' fpm. (and actually reward airlines that reject reports appropriately...?)

Point 2: A difficult one as I am not aware of your current methods.

Point 3: Like you, I am a coder, not a pilot. But to add a little alcohol into the mix, a greased landing would have less of an effect on available runway length in a Cessna at a large airport. That being said, the Cessna has a greater chance of being blown into and shredding the wind sock! I think the -50fpm suggested limit above may cover it.

Point 4: Yes. Though you are possibly doing this already with the reports that are marked as 'manual'.

Point 5: Given the ever increasing number of freeware/payware aircraft, I guess you would need a database of aircraft types/names/derivatives to be able to achieve that. Rather you than me sir.

It would be interesting to add tail strikes and excessive bank/pitch etc (with the obligatory screaming passengers :blink: as I have done with our flight tracker) but I know all too well how much more work this would create for you and most every airline on VACentral!

Once again, let me reiterate that I am NOT a pilot and would gladly be shot down by anyone who wishes to add some cannon fire. :ph34r:

Tim Walters

MaldAir.com / eo3va.com / EUSART.org / MAlitary.org

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Tim penalizing anything under -50ft/ft per min can be very problematic as some VA's have helicopter divisions

and it is quite easy with a helicopter to be under that limit and also with STOL & VTOL Aircraft that will problematic

best regards,

Thomas

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  • 2 months later...

A real pilot had said to me that a landing rate less than 70f/m is UNSAFE for the passengers and the the aircraft.

So my opinion:

1--> YES

2--> Give them something like bonus, or name them Excelent Landing

3--> 50 - 70f/m the unsafe and all over 600-700f/m as high penalty

4--> YES

5--> i think that the manufacters of the airplanes don't have other paramaters for cargo. they don't build different aircraft for the airlines and for the cargo.

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I don't understand the fuss about this. Like Magicflyer already said, it is just for fun.

And on another aspect who's giving the guarantee that all add-ons register the ladingrate

the same way.

Regards,

Cor

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