Question about CRFI
 

A question for landing limits in Canada, can you confirm I have this right?

#1 say the alt airport had a x-wind of 13kts@35’ off runway with a CRFI of .3 Notamed, then it can’t be used. (ie will be CFRI of 3.6)

#2,
Say we have no CRFI reading but the RSC says one inch snow covered, I go to the RSC table and see that is 0.25-.3, say I use 2.7 as my CRFI from my CFS. Lets say I am in a PA-31 and my ldg distance dry and unfactored is 2400feet, I go to the No Discing table over the page and 2400feet at .27 is 5470 feet required. Oh but I need to be able to land in the first 70% of the runway available, 5470x1.3=7111feet.

Is that how you do it? So a PA-31 needing 2400 feet dry will need 7111 to land legally with 1’ of snow, which is very common at some airports.
:confused:

Medium Salsa:

You should look on the bright side of this.

Before we had all these "Experts" making up these charts, graphs and formulas we couldn't fly because we had no one to give us all these wonderful bits of knowledge.

You wouldn't believe the lost time and money we suffered in the far north flying the DC3 's 4's 6's and such because the runways had snow on them and we had no way to ensure that we could actually land on them...so we just sat and waited....

But now we have these really bright people working for the regulator who make it safe with their vast knowledge writing all those wonderful guidelines... of course they first spent years flying under every known condition to become such trusted experts.

So look at the bright side we couldnt fly because we did not know what was safe and what was dangerous...

Don't you just love these guys, making life so simple and of course safe for us?

Aahh.. the luck of the draw, I was cursed by being born to soon and missed all that flight time. :ok:

Oh, well maybe now I can get to fly if I can just figure out how to interpet simple things like CAR's and all these newfangled charts and formulas.....

So when you get it all figured out get back to me and enlighten me. :ok:

Chuck Ellsworth

Chuck, I wasn't trying to be funny, Just trying to work out what Mr. TC and Ms Insurance company wants to see, and basicly, how the hell is it done.....? :ok:

I know, I was only trying to cheer you up.

These idiots are going to regulate and make rules until no one will bother to even go to an airport.

I'm sure you understood my message... We flew for decades in the North under every conceivable condition known to man and did very well using common sense and our skills learned through experience.

I would just love to get one of these guys out from behind their desks and put them in an airplane in those conditions and have a look at what they can do.

Anyhow I understand completely your problem and sympathize with you.. .. I don'f fly commercially in Canada any more so am not up on all their stuff.....We fly on US licenses.

Good luck and dont let em grind you down. :ok:

Chuck

CRFI
 

Medium Salsa,

I do not have the benefit of the CARS or the CFS here but part 1 of your problem looks right. Theoretically you need to have the minimum CRFI value for the aircraft to hold the centerline when the crosswind component is determined. These values are conservative.

Part 2 is a little more interesting. I see that you are using a PA-31 as an example, which in Canada is a CAR 703 (Air Taxi) aircraft. Under these restrictions, there is no requirement to factor your landing distance to 70%, that will be for large turboprops. Your only requirement on a dry day, barring any special considerations or waivers, is to adjust landing weight to allow a landing within 100% of the landing distance under environmental conditions. (credit shall be given for no more than 50 % of headwind and no less than 150% of tailwind, possibly idle power from 50 ft at threshold and 3 degree descent?) Ignore 60% and 70% factors.

Contamination complicates this only a bit further. I assume from aircraft type and lack of CRFI you are operating into a gravel strip in the north. I believe you are using CRFI equivalence values for loose or compacted snow, these are also conservative. You need to apply your coefficient to your normal landing distance like you did and read the corrected distance. This is factoring once. If you were limited by a 70% factor on dry pavement you would need to ensure your weight satisfied the more restrictive of contamination penalties and 70% penalties, but not both at the same time, that would be double factoring. If large aeroplanes were limited by double factoring, they would never fly in the winter in the north.

To sum up a TC guy that I trust, use AFM charts for dispatch limitaions, (in your case unfactored) and use CRFI charts while airborne using the latest info not available at dispatch time and apply them to unfactored landing distances to avoid double factoring. It may be unclear in the CFS but this was the intent of the tables.

One last comment, depending where you fly, the penalties may still be prohibitive without doubl factoring. My advise? Never underestimate the grip that snow covered gravel has on tires. It's far better than snow covered pavement and the crosswind is less than advertised due to shelter from the trees.

Thanks for a great reply, yeah, the CFS wasn't to clear about double factoring. Would have thought that discing would have made a bigger difference between the 2 charts.

OK, So you multiply the length of the runway landing distance by 0.7 for 704 ops and the required distance has to be under that according to the CARS, but is the CRFI legally binding?

If a RFI of 0.3 is reported and I work out that according to the x-wind graph I need 0.42, and I end up off the edge of the runway in a big bent beer can, will TC say “You broke the law, we are going to send you 30 letters over this one” and what about the insurance scabs. Is it law or just Advisory?

So you don't use it in a practical flight plan regarding alt airports? re 25kts TAF x-wind on slushy white stuff?

This and " Verify runway unobstructed when A/G advisory not available" on the approach plates just has the smell insurance companies and TC arse covering here. just my 2 cents worth.

Is it not true that your X/wind numbers in a Piper POH are demonstrated, not limited?

Chuck

Don't know about the Ho, I don't actually fly it, was just trying to keep the example 'simple'.

X/wind numbers in a Piper POH are demonstrated, not limited

Well, if so, demonstrated means I can do what ever I want right?

Are most turbo props limited? out of interest?

thanks

CRFI
 

Medium Salsa,

I think you've got the right idea now. Runway = 4000 ft, 70% factor (if you require it) is adjusted landing weight for a full stop in 2800 ft with brakes only. This is your dispatch limitation. There is no legal need to consult the CRFI chart for penalties until you are within range of the destination and have access to the latest RSC and/or CRFI since much work can be done and much can change while enroute. Then apply your new CRFI value to the full 4000 ft to avoid double factoring. Common sense would dictate that you consult these charts to see what you are getting into before departure. We all know that 100% compacted snow at 9:00 will be 100% compacted snow in March.

I see now that you were asking about alternates, which I believe work the same way. I would be more picky about alternate conditions since this may be where you end up if things are too unreasonable at destination. It might be worth a few hundred more pounds of fuel to get an into wind runway or less crosswind or continuous snow clearing.

If you did end up with a runway excursion, rest assured your company and TC would arm themselves with TAF's, METARS, CRFI's etc to show you why you were to blame. So if conditions become uncomfortable for you, you can arm yourself with these same things to explain a no-op day.

I learned about this stuff after I started to fly up here, so I knew what could be done safely, but it has certainly made no go decisions easier when the charts are my ammunition. The problem in the north is that following the books to the letter would be devastating to an operation, so I have developed a comfort zone based on experience and learning from others, (and the odd scare) and I use the books as my defence when the comfort is compromized. Remember, you can still scare yourself by following the books without using "common" or "bush" sense.

Lastly, two of the turboprops I've flown have a note in the AFM saying 20Kts demonstrated crosswind not limiting, others are less clear.

Bye for now, I am returning for another work week up north with 40 watt bulbs for runway lights.

Planett.

Now you know how to factor the distance,another few hints..Don't trust any reading below .3...In the old scale of JBI..3 was 'poor' braking.In certification circles this mean't that no one knew where you'd end up..Too bad the 'new' index have dropped these references(good poor etc)Aip Table 4 is not very helpful,or should I say explicit.If the tower or FSS says 'poor' ask him where the other guy stopped on the runway.
The crosswind chart(table 3)stipulares that one can land ,with a DRY runway with a crosswind of 45knots!!And a CRFI of .3 with 10 knots??I'd cut the values down to 5knots with CRFI.3 etc..
Cheers:O