Maximum Operating Speed

[Guest Sjaako]

Anyone?Cheers Sjaako

[Guest Sjaako]

Hi Again,Surely someone must have noticed the fact the T7 does not go beyond 330kts indicated?Cheerio Sjaako

[Iain Sealey 1]

At cruise levels IAS should not be used for speed. Mach number should.Due to density altitude as you climb at a constant IAS your TAS (The only speed, rest are pressures) and your Mach number rises. And in the decent at a constant IAS your TAS and Mach number drop so you are going slower, but for the same IAS.In the cruise say between FL300 and FL410 (Max cruise ceiling of the 777) between 250 - 290 KIAS should tranlate to around Mach .84 which is the standard 777 cruise speed.So to the answer to your question a 777 will go beyond 350 KIAS but only at a low desity altitude,ie SL - 10,000 - 15,000ft.The FMC will optimise your cruise, climb and decent speeds for you and revert between IAS and Mach number automatically, according to the CI used, for example British Airways use 100 as a CI on the 777 fleet.Just remeber 330kts IAS at 33,000ft, would will be well over the design limit speed ov the aircraft.Cheers

[Guest Sjaako]

Hi,In my 777Lr the maximum speed is showed as 350 knots, ie that's where the barbers pole starts.Is there a difference between the 777er and lr? Since the manual I have states the maximum operating speed is 330 knots.Cheers Sjaako

[Guest NormanB]

Thanks Iain.

[FOD 23]

IainAgree that IAS is a measure of pressure

[Guest Not 40W Again]

Sjaako, Looking at your other posts on this forum you obviously have a fair knowledge of aviation and the 777, I doubt Iain's post has answered your question. It is, however, quite dificult to know what information you want from the question you have asked. If it relates to the VMO on the REAL 777 that is 330 knots on all models (as far as my research goes). If it relates to the PSS 777 the VMO (barbers pole) seems to vary and is often above 330 Knots. Something for PSS to look into? AndyPS Before anyone jumps in the variation was between models at 3000', so MMO was not an issue.

[Iain Sealey 1]

777-200ER: VMO 330KIAS MMO M0.87777-200LR: VMO 330KIAS MMO M0.89777-300: VMO 330KIAS MMO M0.89777-300ER: VMO 330KIAS MMO M0.89These are from FAA certification documentsSo the easy question to answer, no the 777 will not go above 330ktsCheers

[Guest Sjaako]

Hi All,Thanks for all your replies, maybe my question was not clear enough.....Max operating CAS is 330 knots until Mach becomes more restrictive. When I fly in my T7 the barber pole start at 350 knots which is not the case in the real one since it always sits at 330, or config limit, or MMO. So I'm saying the speed tape in the model is incorrect with the red line at 350 knots. Does anybody else have this or just me?Thanks again,Sjaako

[FOD 23]

SjaakoI have used 3 different installations of the 777 on 3 different systems - all have a VMO Clean of 350kts. In fact I have just cruised my 777 at 4000 ft and 348kts with no problem. I guess perhaps that 350 kts was just a slip of the programmers keyboard.John R

[Guest Sjaako]

Thanks,So I suppose this is now flagged as a program error.Cheers Sjaako

[Johan_Dees 84]

It might be able on lower level to do much more, but SAFE operation is around 330 knots.Its an pilot recommended speed.Like a manual for a vacuum clear stating that 20 minuts of use needs 1 hour of cooling, while it may run for 50 minuts without overheating, depending on the circumstances.JohanA LITTLE LESS CONVERSATION, AND A LITTLE MORE ACTION PLEASE!HELP:http://support.microsoft.com/?kbid=238882

[FOD 23]

Hi JohanAppreciate that the aircraft is easily capable of exceeding VMO in certain conditions and also that airlines will choose to operate in practice at below VMO for many reasons

[Johan_Dees 84]

A typo perhaps?JohanA LITTLE LESS CONVERSATION, AND A LITTLE MORE ACTION PLEASE!HELP:http://support.microsoft.com/?kbid=238882

[Guest Sjaako]

Hi All,Well I can assure you that under all normal conditions the REAL aeroplane has 330 knots as the start of the red bar (Barbers pole). Not with flaps or gear down of course.I am sure that my airline would not be very impressed if I flew the aircraft at 335 knots, and a subsequent chat would certainly follow. So it can't quite be seen as a vacuum cleaner........Cheerio Sjaako