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Advise on Flight times

Started by Jim Caudell, Aug 11, 2014 00:41

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Jim Caudell (1163)

Hello all,
When I check my logbook after a flight, all of my flights are about 0.1 or 0.2 past the scheduled landing time.
I don't think it is a program problem.
I use Radar Contact, Active Sky 2012, FS2CREW for the PMDG J41
I have worked out the time to start everything so I am pretty close to scheduled departure time.
The last two flights I did I cruise near the EGT limit, but had a lot of ice and anti ice was on most of the way.
I don't know if it is the weather slowing me down a little, Radar Contact or just me.
I did have two flights where I arrived a little early.

Any suggestions. I know it is I am not missing by much, but it bugs me that I can't get it closer.

Thank you, and clear skies and good winds

Chris Liu (1001)

#1
Some notes on flight durations
I do all the flight schedules in a program called Airline 6 as it gives realistic blocks off/on times (remember that's how we time flights at Intercity, engines on until engines off), but obviously it's not going to be perfect for every single route and aircraft combination. Providing you're not looking at a sea of orange or red in your logbook (which you're not) then you're not doing badly! Also, some turnarounds are longer to give some slack in the schedule to absorb delays.

Delay causes

I use a weather engine and FS2Crew and (looking at my logbook) I generally arrive a little early, but I fly online so perhaps Radar Contact is slowing you down somehow? Beyond abnormal weather, the normal causes for a delay are ATC/traffic, circuitous routing, suboptimal cruise level or a very lengthy taxi (I've excluded tech issues as the FSX J41 generally doesn't go tech on you, unless you burn the engines).

Speeds and ice in the J41
It's normal to operate the J41 at the EGT limit (VRL) for the entirety of takeoff and climb (pitch for 180 kias), and even in cruise if required, although you should reduce engine RPM for each phase (takeoff 100%, climb 98.5%, cruise 97.5% and descent 96.5%).

I don't reduce to cruise RPM until I've reached cruise speed though, typically within 15 KIAS of Vmo (can't remember exactly what TAS this equates too, might be 285 KTAS?)(there is a tip on setting cruise power in the Intercity J41 FAQ, but again don't reduce thrust/RPM until you've accelerated significantly).

Extended periods in icing conditions do present a challenge in the J41, but if necessary you can increase to 100% RPM to punch through the icing layer (this increases EGT VRL so you can then increase thrust).

Cruise levels in the J41
On some (not all) your flights, you're cruising 2000 ft too low; as a rule of thumb aim for FL180-190 on J41 legs between 45 and 75 minutes. Longer flights you can usually go for FL200 to gain a little extra TAS, and for sub-45 minute flights you can consider FL160. Generally you should never be under FL150 nor above FL210 (the J41 isn't a happy bunny above FL200 unless you're rather light).

Summary
I hope this helps and hasn't bored or confused you to death Jim! Having reviewed your logbook your routing looks good so the only certain thing I can suggest is cruise higher sometimes; attain at least FL180 on the majority of J41 flights and avoid FL160 except for very short flights.

EDIT: Bit of a lengthy post so I added some headings to make it easier to read!

Greg Marshall (1151)

Some good reading here!  :)

Chris Liu (1001)

Perhaps I should shove something in the Jetstream 41 FAQ regarding cruise altitudes (the power setting and icing stuff is already in it)?

I had to eat my own words last night though and force the J41 up to FL210 to avoid turbulence, but fortunately we were pretty light and not in icing conditions so it was fairly quick.

Greg Marshall (1151)

Cruise levels would be good in the FAQ  :)
I think my Edinburgh to Inverness flight is normally flown lower so I will get it up to FL160!

Chris Liu (1001)

#5
That's scheduled for 55 minutes block to block, so FL160 should be easily attainable  :) Providing you don't go silly with the fuel load (our J41 FAQ states trip fuel plus 1200 lbs typically) FL180 is achievable as I've used it on London City-East Mids, a mere 45 mins.

Anything much above F180 on a block-to-block time of under an hour though is not going to be beneficial. Looking at real world flight plans filed by Eastern Airways, they use FL160-FL180 for 45 minute JS41 legs.

Having said all that, Loganair fly Edinburgh-Inverness at FL125 in a Saab 340 ??? That's gotta be costly (and slow)!

Greg Marshall (1151)

FL125 is crazy! Would that not normally be right in the middle of icing conditions too?

Jim Caudell (1163)

Thanks Chris for the advice.  :D
I try to follow the NATS routes and levels. The ones you suggest sounds good. I always had trouble deciding on which FL to use. This will help a lot.

If there is a SID or STAR I try to get the non runway specific part into the flight plan for RC4. If there is none, RC4 seems to do a good job of routing, but could be slowing me down a little.

I think I have been adding too much fuel too.   ::) I will try the trip fuel + 1200 lbs and see what I come up for FOB and see what that does.
I usually travel with 22 pax, and the cargo/luggage from the J41 tutorial. It might be a little too much too. I will try lighter weights and see how that does.

Thanks again for all the information and help, it is much appreciated

Sean Donno (1110)

It can be done  ;)


I've just done my 43rd flight and managed to get this bang on  8)


Engine start bang on departure time, which starts the logger (DH8D) and parked on the stand with 2 minutes to spare, so spent this checking everything (ahem. Thoroughly!) before shutting down bang on arrival time  ;D


[smg id=236]

Chris Hulme (1003)

Quote from: Sean Donno on Aug 19, 2014 22:09
It can be done  ;)


I've just done my 43rd flight and managed to get this bang on  8)


Engine start bang on departure time, which starts the logger (DH8D) and parked on the stand with 2 minutes to spare, so spent this checking everything (ahem. Thoroughly!) before shutting down bang on arrival time  ;D


[smg id=236]


We now expect you to maintain this precision for every flight you do  ;D

Sean Donno (1110)

Maybe in another 43 flights I might manage it again  :-[

Jim Caudell (1163)

Hey guys,
I think I might have figured my times out.
With the information I have gotten from these replies has been very helpful and informative.
I think where I am loosing the time, is the taxi in to the gate. I usually call for the GSX follow me car, and I think the time I am waiting for him to show up is the delay and killer.

I have just moved, and have not been able to fly and try it out. But I am itching to give it a try.

Thanks again for all the information on flight level and other insights on getting the times right.

a little modified saying  May the wind be always at your back and the runway rise up to greet you.