Allowances for the 250kt rule

dgor · Post by **dgor** » Thu Jul 06, 2006 4:40 pm

Hi,

I think that a few allowances should be made for the '250kt under FL100' rule. For example, it's not the pilot's fault if a sudden tailwind speeds him up a bit, is it? Or if turbulence sends him below 10,000ft when he was happily at 11,000ft at 285kts?

Just an idea

FsNovice · Post by **FsNovice** » Thu Jul 06, 2006 5:37 pm

i agree with this point and also some planes need to disobey this rule like for example SST's and so forth to remain in the air.

Post by **cmdrnmartin** » Thu Jul 06, 2006 6:31 pm

Most planes don't sit at 250 on climbing and descending, and are instead given airspeed requests by controllers.

Hpwever, i've found that I never get a penalty if i set myself to 235 kts. Which coincidentally is a good climb and descend speed to be at.

Matthew · Post by **Matthew** » Thu Jul 06, 2006 7:12 pm

cmdrnmartin wrote:Most planes don't sit at 250 on climbing and descending, and are instead given airspeed requests by controllers.

Hpwever, i've found that I never get a penalty if i set myself to 235 kts. Which coincidentally is a good climb and descend speed to be at.

I always manage fine

from take off to 3,000ft i am at 150ais
3,000 to 7,000 i am at 185 ais
then 7,000 to 10, 205

10 untill cruise 240

and cruise is between 255 and 270

same for desent

tall_guy_pete · Post by **tall_guy_pete** » Thu Jul 06, 2006 10:03 pm

I don't think we shuld change this at all . Dgor .. you must be descending to fast for your speed to increase.

Im always below 240knots (most of the time) unless i forget that im on manual throttle ...

e.g. with the B757 and the 747 I cruise at 210knots under FL010 with the aid of flaps with the 747

CAPFlyer · Post by **CAPFlyer** » Thu Jul 06, 2006 10:20 pm

I agree that for the most part there is no need to remove the restriction. The only time when the 250 knot rule becomes a problem is for aircraft like the 747 or 777 when very heavy, then they may need to fly up to 280 or 290 knots to achieve a fuel-efficient (read- slats retracted) climb. However, for a fuel penalty, they can remain slower and still fly okay. I've noticed that I don't get dinged as long as I'm flying under 260 knots, so you do get a 10-knot window to play with to help out some.

Also, what are you guys flying to be going that slow in the climb? If you're flying a jet like a 737, you need to be sitting on that 250 knot mark to 10,000 and then accelerate to the 270-290 knot range for cruise climb. Any slower and you're burning a lot of extra gas.

tall_guy_pete · Post by **tall_guy_pete** » Thu Jul 06, 2006 11:56 pm

Normally 280 for most aircraft

Blackhawk1 · Post by **Blackhawk1** » Thu Jul 13, 2006 12:01 am

All I know is that I've been doing some practicing in the Concord, and it is good it was training. I have my autopilot set to keep me at 240kts but the problem is... that won't keep the bloody SST flying!

SJDobby · Post by **SJDobby** » Thu Oct 26, 2006 12:31 pm

Not sure which SST you are flying, but in my limited experience (with the SSTSim aircraft, not the PSS one) even at max takeoff weight I think you are still looking at sub-250kt V2+10kt speeds. I haven't flown the SST for quite a while now but I don't recall ever needing more than 250kts in the initial climb (and I usually had a max t/o weight setting for EGLL-KJFK).

That aside, I occasionally come unstuck with the autothrottle [PMDG737, LDS767 especially] being a bit inaccurate at holding the VNAV-set 250kt speed limit. This could in part be down to the relatively-low-spec system I currently use (FS framerates rarely much above 10/15fps) so perhaps it takes the system that little bit longer to identify speed changes and react to them.

It's no big deal - treat it as part of your procedures (if necessary on your aircraft) to manually dial in lower speeds (I tend to use 240kts below 10,000).

carthorse · Post by **carthorse** » Wed Nov 15, 2006 1:09 am

tall_guy_pete wrote:I don't think we shuld change this at all . Dgor .. you must be descending to fast for your speed to increase.

Im always below 240knots (most of the time) unless i forget that im on manual throttle ...

e.g. with the B757 and the 747 I cruise at 210knots under FL010 with the aid of flaps with the 747

Sometimes ATC will waive the 250kt restriction and ask you to keep your speed up for spacing. Would be a shame to loose 5% of your profit to help out ATC.

Ionathan · Post by **Ionathan** » Wed Nov 15, 2006 10:10 am

I agree with carthorse. Things may differ when live ATC comes into the game.

AK Cargo Pilot · Post by **AK Cargo Pilot** » Wed Nov 15, 2006 7:50 pm

You shouldent be riding right on 250 anyway below 10000ft, and at least in a big plane a gust of wind aint going to speed you up to bad, so just take the procautions and stay like 15-30kts below 250 and you will be fine.

michiyoshi · Post by **michiyoshi** » Tue Dec 05, 2006 5:59 am

The question you should be asking is, does the program read IAS or Ground speed?

I'm pretty sure it'll read IAS, in which case, changes in wind direction won't have a big effect on IAS below 10,000 feet, unless you hit a wind shear that's about 30-40 knots in different directions.

highsea · Post by **highsea** » Fri Dec 08, 2006 1:28 am

the 250 knots below 10,000FT doesn't apply on departure as long as your planned altitude is above 10,000FT

CARS http://www.tc.gc.ca/CivilAviation/Regse ... T6/602.htm

a person may operate an aircraft at an indicated airspeed greater than the airspeeds referred to in subsections (1) and (2) where the aircraft is being operated on departure or in accordance with a special flight operations certificate - special aviation event issued pursuant to section 603.02.

FAA http://ecfr.gpoaccess.gov/cgi/t/text/te ... 3.10.2.4.9

(d) If the minimum safe airspeed for any particular operation is greater than the maximum speed prescribed in this section, the aircraft may be operated at that minimum speed.

Climbs speeds in a 757 is 220 IKTS to 3000FT then 250 IKTS after 3000FT.

Alky · Post by **Alky** » Fri Dec 08, 2006 2:53 am

All of this chatter is meaningless when the client sees something altogether different than what you see in the cockpit!!

This was in a CRJ-200... for the whole flight, on several flights

FSAirlines

Allowances for the 250kt rule

Allowances for the 250kt rule

Aloowances for the 250kt Rule