PPRuNe Forums - View Single Post - F100 - Overshot Runway at Newman Airport (9/1/2020)
Old 11th Jan 2020, 16:27
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CurtainTwitcher
 
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Originally Posted by airdualbleedfault
Newman is about 200m longer than the full factored LDR for a F25 wet runway landing in the Dutch oven, whilst I don't know all the extenuating circumstances, parking a jet in the mud is most definitely not a good result and I'm pretty sure most of the inhabitants of BS Castle would agree
Interesting, the relatively slender margin of the "black and white" wet landing distance assessment. As the FAA have now discovered, black and white factoring isn't so clear cut and won't protect you. Highly relevant is the FAA SAFO 19003 Subject: Turbojet Braking Performance on Wet Runways.

In a nutshell, the FAA are saying you need to add 30 to 40% factoring, not 15%. We haven't even begun to scratch the surface of even moderate rainfall on ungrooved runways, should be considered contaminated for braking action. Heavy rainfall is defined as >50+ mm in the last 24 hours by the World Meteorological Organisation.

I do also note that the BOM rainfall figures for Newman on the 9th Jan indicated 70+ mm of rainfall between midnight and 0900 and 140+ mm in the previous 24 hour period. The ATSB incident status page indicates the incident occurred at 0723 WAST, the BOM observations are posted below with the rainfall since 0900 in the far right column.

Unfortunately, all too predictable over-runs in similar circumstances on short wet ungrooved runways will continue to occur until the operators start taking the SAFO recommendations into account and increase factoring during arrival periods of moderate to heavy rainfall.











BOM Mount Newman observations 09-Jan-2020, rainfall since 0900 far right Column


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