LRC Accuracy

[Kyle Sanders]

Hello,

 

I am wondering if the JROLLON CRJ2 is programed according to Bombardier LRC charts.

 

I planned a flight yesterday from KATL-KTPA and had planned for FL390 according to many calculations but the most important one being the LRC altitude selection chart (attached) which said I should be at FL390.

 

But I reached the 300ft/min climb ceiling at FL330 and had to level off there.

CRJ Flight Planning LRC.pdf

Edited December 11, 2012 by Kyle

[cessna729]

Hi Kyle, What was the OAT at your alt and what weight were you? and were you using any engine bleed air/services ACU's, anti ice ect A/I)at the time? I havn't got the correct chart to hand at the moment, but given the shape of the curves on the one you attached, my guess is that above a certain weight or temp your not going to get this CRJ up to the mythical FL410 (or if you do get there you won't be staying very long. http://en.wikipedia.org/wiki/Pinnacle_Airlines_Flight_3701

Note: In the accident report is the paragraph:

"FCOM volume 2, Operating Limitations, pages 30 and 31, dated June 2004, stated that “the FMS calculated thrust setting must not be used if the pressure altitude is greater than 36,000 feet.” The Bombardier chief pilot stated that the reason for the FMS limitation above 36,000 feet was because of the inaccurate calculations above that altitude. Further, according to Bombardier, at altitudes above 36,000 feet, the conversion from static air temperature to the International Standard Atmosphere (ISA) deviation is ncorrect within the FMS, resulting in an error in the N1 indication at those altitudes. (A detailed explanation of ISA appears in the next footnote.) Bombardier’s Flight Planning and Cruise Control Manual and Quick Reference Handbook contain charts that show the proper N1 indication for altitudes between 36,000 and 41,000 feet."

cessna729.

Edited December 11, 2012 by cessna729

[Kyle Sanders]

Well this is informative. I'm on my cell right now... Do you har these updated charts?