spxdriver said:
Keep in mind, I'm talking wet runways with anti-ice on. According to EMBs own info, the airplane requires in excess of 6500' at sea level.
I call BS on that. I don't recall EVER sending you any wet runway tab data as I don't know that I have ever even had any. (Apologies in advance if I have. It is either news to me or the resut of age dimming memory.)
Where are you getting those numbers? I'll ask you again. What page and what revision number? Does it have a date?
There are only two places I can think of that *MIGHT* have wet runway takeoff numbers. A JAA AFM and APG. I don't know that even Embraer Takeoff Analysis has wet runway takeoff data and I'm digging for my CD as I type (haven't used it in awhile).
The closest gudance is in AOM Vol 2 Revision 14 - 1-04-15 130 02 which states:
Slippery and contaminated performance accountability are required by JAR, but not by FAR. FAA allows operators to use it at their discretion (see FAA AC 91-6A and Draft AC 91-6B).
A runway is considered contaminated when more than 25% of of the surface used is covered with:
- Standing water with a depth exceeding 1/8 inch (3 mm).
- Slush or loose snow with a depth equivalent to more than 1/8 inch (3 mm) of water.
( ...)
Takeoff performance for contaminated and slippery runways can be computed through the EMBRAER Runway Analysis Software using the AFM - ETOAS Method (refer to Supplement 7 of the AFM). The output data is valid only as guidance (emphasis mine) and it does not consider the use of reverse thrust for airplane stopping.
Dont know about EMB's numbers because we run our own. We take weight penalties when running anti-ice on not added runway length. Worst I have seen is about 3000lbs off of MGTW. I cant imagine a Legacy departing anywhere close to MGTW(again dont fly one) at any time though unless they are running in an airline type interior or possibly max gas.
We take off regularly (Legacy 600 and equivalents) with a full boat and as much gas as we can take (depending on the misssion). It happens. BOW around 29K-30K and can carry 18K # of fuel, MTOW 49,604#. (The Legacy 650 has higher MTOW, fuel capacity, thrust, etc. and performs better as a result.)
And you are correct on the penalty. I ran the numbers for SPX's own 4,800' long strip in both directions (from -10 to +10 the Legacy 600 will fly at roughly 45,500 lbs, MORE than plenty to go 2,500 NM: the 650 will do much better) and the weight penalty is under 150 pounds for anti-ice on. With ten knots of headwind I get all that weight back. I will see if the EPAS (or ERAS I guess it is called now) gives any output for contaminated surface but I seriously doubt the penalty is 1,500 feet.
The only time I ever even considered this an issue was in an EMB-135 RJ coming out of Florida when it was raining buckets. It didn't seem prudent to takeoff into a thunderstorm so I delayed my departure twenty minutes. If you have enough water over a grooved runway that it is considered contaminated then it is probably a good time to set the parking brake and rethink things for a bit, no matter WHAT airplane you are flying.
