Landing on a flodded runway and in heavy rain

[manucordier]

Hi,

I've read that the best course of action when landing on a flooded runway and in heavy rain is to land firmly, lowering the nose wheel as soon as possible in order to obtain all the wheels on the ground for max friction and thus max braking action.

Do you agree ? Do you have any additional info ?

I have read also that you must increase your approach speed . Why is that ?
Is it to prevent the hazardous effect of an eventual windshear or gust which could temporarily decrease the airspeed and provoke a dangerous loss of lift ?

I thought that with a flooded runway it was better to land with the slowest possible airspeed to avoid hydroplaning. Is that right ?

Could someone add more information please ?

Thanks,
Emmanuel Cordier.

[de facto]

Positive landing is the way to on a contaminated and distance limited(test pilots are not paid to make soft landings).
Why would you land on a flooded runway in heavy rain in the first place?windshield wipers have a limit speed;-)

[dcoded]

Approach speeds may be raised because heavy rain increase stall speeds

[Neptunus Rex]

Flooded runway? Increase speed - certainly; as you go around and divert!

[Northbeach]

manucordier,

It is best to consult the manufacturer’s flight manual for a particular aircraft and apply their recommendation(s) (if they exist) for operating in adverse weather and runways conditions.

We have guidance for adding speed to our approach speed for higher and gusty winds on the surface. Those additives increase our speed on final, but I do not recall a specific additive for ‘wet” or “flooded” runways. It will depend on what aircraft you are talking about. We have wet runway analysis for landing (and takeoff) data as well as surface contamination; but it doesn’t specifically address a “flooded runway”. I would be leery of landing on any runway that was described as flooded (I’m talking about the 737 I currently fly, not the Cessna 206 in the “bush” {done that as well & a different set of rules apply}).

Normally approach speeds are increased to provide more potential energy to compensate for the fluctuating airspeeds and the possible encounter of decreasing performance tailwind windshear; should one encounter it on final. Not that you would intentionally fly through known windshear on final. Remember: “Thou shall maintain thy flying speed (critical angle of attack) least the ground rise up and smite thee”.

Hydroplaning is a function of the condition of the runway, tires and tire pressure (9 X the square root of the tire pressure: if my memory is correct-if not you can bet somebody will correct me).

Grooved runways are runways that have been cut to provide small channels for water to run off the landing surface allowing for superior stopping performance.

For the brakes to stop the airplane the weight of the airplane must be on the wheels and not carried by the wings. Consequently “lift dumpers/ground spoilers” have a significant impact on stopping distance. If the wings are still generating lift and “flying” the airplane the brakes are not going to be as effective in stopping the airplane.

If auto brakes are available, augmented by antiskid, their use will improve braking efficiency. Obviously, other things being equal, a heavier aircraft will take longer to stop, so landing weight will have a bearing on stopping distance as well.

Neptunus Rex is of course correct if the runway is "flooded" we are not really going to land an airliner there........although "Sully" and company pulled off a commanding performance on a "flooded" runway in an Airbus not that long ago.

Respectfully,

Northbeach

[INNflight]

An increased approach speed comes natural if you think about it. Heavy rain influences the airflow over your wing quite a bit, thus increasing your Vs.

This of course also results in a longer landing distance, in addition to the fact that braking action is reduced. That's why a rwy may be good to use when dry but off limits in contaminated conditions.

Also (if your acft has it at some point in your career), obviously max use of reverse thrust is helpful.