Accounting for Contaminated Runways

[mutt]

In one of our present discussions regarding V1, the following statement was made.

The V1 data presented to many of us flying older equipment makes NO adjustments of any kind for icy or wet situations. The same MTOW is used.

Unfortunately while this may be an extremely lax interpretation of the FAR’s, it is legal.

But as a crewmember, would you be happy to accept the fact that you will go off the end of the runway due to your companies’ policy?

What other options are available to them?

Mutt. :)

[Slick]

Yes not very good is it. Who's doing this I wonder ?. Same RTOW for an icy or wet runway, your not even gonna JUST go off the end are you !.

I would try and get this sorted ASAP legal or not, if no one wants to listen - leave. Rolls off the tongue easy I know, but there is a preservation issue here for probably more than one person, who knows maybe I will be sitting down the back one day, and I for one would not be amused.

Best rgds

[ 15 August 2001: Message edited by: Slick ]

[Chimbu chuckles]

CAOs (Australia) increase the factoring by 15% for contaminated runways. Thats X 1.92! Can't remember off the top of my head if they/we do something else for ice on the runway....I shall go and look it up! :)

Seems reasonable to me.....at least it's something, heard the FAA's attitude recently and was surprised to say the least :eek:

[Roadtrip]

Last winter I saw many European 747s taking off from a Northeast US airport with the first half of the runway "half inch snow/ice" and the last half of the runway contaminated with "3" packed snow and ice." We waited 3 hours for the airport authorities to clear the runway, but the Euro 747s took off one after another. They were heavy and had V1s and Vr well into the contaminated portion. Abort??? No way. They'd have been in the water. I couldn't believe what I was seeing.

[quid]

We have to clarify a few terms used in this discussion.

"Contaminated" in the strict legal FAR sense means a build up of some sort that retards ACCELERATION on takeoff. If it is hard packed snow/ice, and the temperature is around -3C or colder, the runway is considered "dry" for the purpose of MTOW calculations, and NO weight reduction is required. (I don't agree with that, but that's the rules.)

The 1.67 and 1.92 figures are used for Landing Field Length, and have nothing to do with degraded braking action on an aborted takeoff.

When we're talkng landing, the runways are considered "dry" or "wet and/or slippery", I have no landing charts that have the word "Contaiminated" printed on them. (Mutt, do you?) The pages that we distribute to the flight crews have the Mu, Tapley, Bowmonk, etc. values printed on them for information to be used in decision making. They are not regulatory.

When we pilots use the word "contaminated", we know what we mean, but it's not necessarily the same as the regulatory agency. :(

[Slick]

If it is in my opinion a rough runway I will not go/delay if I am not happy with the ADVISORY figures. My boss will stick with me on this, he has in the past. I Can't have it any other way, lives are at stake, are they not ?.

Take care guys

[411A]

When I flew for a particular South Asian airline and the weight for takeoff was at the max for the (wet) runway, I had a little discussion with the FO/FE and suggested to reduce V1 by a factor (but not less than Vmcg) to enable us to stop if needed. This usually resulted in an approximately 10-12 knot reduction. Unfortunately the runway analysis charts gave no guidance in this regard, and the company was not inclined either. However, if one looked very deep in the AFM their was "for reference only" data from the manufacturer. When this was pointed out to the crew, everyone thought it was a better idea than sliding off the end. The end result of course was that if there had been an engine failure, the resultant screen height would be reduced.
Not scientific, but it works.

[m&v]

As you know the industry paid attention to 'slush'after the BEA takeoff accident late 50's.FAA take into account 'slush'and data available in the AFM.the difference between FAA data and the JAR's is the 'wet' screen height adopted by the BCAR,thence the JAA.With 'Contam'ops,JAA rules reduce the screen height to 15'and the V1 is reduced to enable the accel'stop! to stop in the distance provided.As the UK has always contended it's a compromise towards safety.The same 'info'is now avail'to Boeing User's under 'perf package 'B',used by all the JAA fleets!It cost money and in the gen'case'payload-but it is Safer.Why is this Safer procedure not used in the 'states-because the ATA(fleet owners)won't compromise on the payload,and the FAA won't use the 'new'data(B777)on the 'old'types.. :eek:

[mutt]

Quid,

Although the FAR’s haven’t changed, its interesting to note how the interpretation of them has. Our older B747’s and the L1011 which 411A flew had a basic contaminated runway correction of reduce RWY LWT by 10% and V1 by 15 kts . This wasn’t very scientific, but it went someway towards acknowledging the effect of the reduced friction between the aircraft tires and runway. Even though this wasn’t required by the FAA.

With newer aircraft and the computing abilities that came with them combined with directions in the form of FAA AC-91-6B, we were in a better position to judge how we wanted to operate off contaminated runways. Interestingly, while we were just reducing 10% off the RWY LWT for ICY runways, we ended up prohibiting operations from them due to the ineffective braking action. (Wet Ice gives a braking action of 0.05 to NIL).

It amazes me that 10 years after the first issue of AC91-6, it still hasn’t found its way into the FAR’s.

M&V states the ATA(fleet owners)won't compromise on the payload. I guess that as sad as that sounds, it’s true!

M&V The data available from Boeing for FAA operators is based on FAA AC-91-6B, while this doesn’t directly address the screen height of 15 feet, it was adopted in the advisory data of the time. Therefore you will find that AC91-6B and JAROPS1 are almost the same.

For most modern aircraft, the data is available, therefore IMHO, regardless of the requirements of the FAR’s, any operator who ignores corrections for contaminated runways is grossly negligent.

Mutt. :)

[How's it Hanging]

Unless operating out of really short strips, it is not a big deal in the Dash 8, but on a wet runway we reduce V1 by 6 kts. If takeoff in icing conditions also a reduction in RTOW.

[Ignition Override]

Does anyone out there operate through Detroit (DTW) in the winter? Do you remember the constant departures from (formerly 21C) 21R? Nobody lands there often in the winter. Once I asked tower what the braking action was on 21C and they said something like "we don't know, nobody has landed on it in a while".

Would YOU accept it (8400') for your departure runway, or a similar runway somewhere else?

[LRdriver]

while we are on the subject,
Does anybody know if there is a reference to grooved runways in the JARops? Do you consider them wet or dry after a rainshower?

This due the fact that we operate into fields where it makes a huge diff Max Land mass-wise if a rainshower "changes the colour of the landing surface". There was an old reg in the danish regs but does it exsist in the JARs?

[stator vane]

mutt;

where does that bit about the slush HELPING the aircraft stop fit in this???

i still haven't found anything to validate that other than the slides you sent.

if that is true then if the slush is thick enough, then all is back to dry runway weights???

cheeky i know, but i had to throw that in!!! :D