Narrative:

We were scheduled to operate a flight from mmqt. Conditions at the time were winds 110/15; temperature of 16C. Due to the winds; runway 9 was in use. Upon checking our runway analysis numbers; we determined we were unable to depart runway 9 due to the requirement of a special engine out departure procedure to avoid terrain which placed us at an overweight condition. We did not depart.terrain in mmqt directly to the east of the airport shows elevation contours in the jeppesen charts at 7000 with peaks at 7186 and 7560 approximately 11 miles east of the departure end of runway 9.this information was relayed to the customer to notify them of the delay. Upon further checking for solutions; operations discovered [landing analysis data] provides an option for a non-special single engine dp (departure) that was not in the original runway analysis generated. This non-special dp provided higher weights that would have allowed a takeoff from runway 9 with the calculated takeoff weight that night.to the best of my knowledge; in the absence of a special engine out departure procedure; the standard engine-out (non-special) procedure is to fly runway heading while flying our engine failure profile per our manuals. In this case; even though the new [landing data] for the non-special procedure would have allowed for a takeoff from runway 9; the profile would have been to fly runway heading during an engine failure on takeoff.this seemed problematic to us as a crew considering the terrain to the east is only 10-11 miles away and given the required climb gradients for a single-engine climb; we would have covered approximately 9 miles before reaching our acceleration height (~7300 ft) and then would have accelerated at a height below the peaks to the east of the airport.seeing how a runway heading on departure doesn't account for drift; use of such non-special dp seemed illogical at an airport with high terrain surrounding it. It was interesting to see that [the landing data] allowed for that option. Typically; if there is an obstacle ahead that requires avoidance; a special dp is generated to avoid it as is the case in mmqt where a turn back towards the airport is required to avoid the terrain. However; if the navaids required to track on the special dp are out of service; one would think that a non-special dp would restrict the weight even further to require higher performance for a steeper climb gradient to clear the obstacle. This was opposite of what the [landing data] data showed out of mmqt that night.ultimately; we decided as a crew to not depart even with the new numbers due to our concern of erroneous data.looking through the manuals; I could not find specific information on interpretation of [landing data] for engine-out departure procedures. It would be beneficial to the pilots to have more guidance on how to fly non-special dps and to also list whether compliance with a special dp is mandatory in mountainous terrain regardless of whether it is IMC or VMC.one thing that concerns me is that in a situation where a NAVAID required to fly a special dp becomes inoperative (e.g. Qet VOR in mmqt as required for the special engine-out dp); [landing data] would then have to generate numbers that allow for a straight out climb not requiring the NAVAID which would have crews flying straight into terrain.if flying a special dp in mountainous terrain is mandatory for terrain clearance; [landing data] should not allow for an option to fly a straight-out engine out departure.

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Original NASA ASRS Text

Title: Air Carrier Crew reported they decided not to depart MMQT due to a combination of weight and runway in use due to the terrain surrounding the airport.

Narrative: We were scheduled to operate a flight from MMQT. Conditions at the time were winds 110/15; temperature of 16C. Due to the winds; runway 9 was in use. Upon checking our runway analysis numbers; we determined we were unable to depart runway 9 due to the requirement of a special engine out departure procedure to avoid terrain which placed us at an overweight condition. We did not depart.Terrain in MMQT directly to the east of the airport shows elevation contours in the Jeppesen charts at 7000 with peaks at 7186 and 7560 approximately 11 miles east of the departure end of runway 9.This information was relayed to the customer to notify them of the delay. Upon further checking for solutions; operations discovered [landing analysis data] provides an option for a non-special single engine DP (Departure) that was not in the original runway analysis generated. This non-special DP provided HIGHER weights that would have allowed a takeoff from runway 9 with the calculated takeoff weight that night.To the best of my knowledge; in the absence of a special engine out departure procedure; the standard engine-out (non-special) procedure is to fly runway heading while flying our engine failure profile per our manuals. In this case; even though the new [landing data] for the non-special procedure would have allowed for a takeoff from runway 9; the profile would have been to fly runway heading during an engine failure on takeoff.This seemed problematic to us as a crew considering the terrain to the east is only 10-11 miles away and given the required climb gradients for a single-engine climb; we would have covered approximately 9 miles before reaching our acceleration height (~7300 ft) and then would have accelerated at a height BELOW the peaks to the east of the airport.Seeing how a runway heading on departure doesn't account for drift; use of such non-special DP seemed illogical at an airport with high terrain surrounding it. It was interesting to see that [the landing data] allowed for that option. Typically; if there is an obstacle ahead that requires avoidance; a special DP is generated to avoid it as is the case in MMQT where a turn back towards the airport is required to avoid the terrain. However; if the NAVAIDs required to track on the special DP are out of service; one would think that a non-special DP would RESTRICT the weight even further to require higher performance for a steeper climb gradient to clear the obstacle. This was opposite of what the [landing data] data showed out of MMQT that night.Ultimately; we decided as a crew to NOT depart even with the new numbers due to our concern of erroneous data.Looking through the manuals; I could not find specific information on interpretation of [landing data] for engine-out departure procedures. It would be beneficial to the pilots to have more guidance on how to fly non-special DPs and to also list whether compliance with a special DP is mandatory in mountainous terrain regardless of whether it is IMC or VMC.One thing that concerns me is that in a situation where a NAVAID required to fly a special DP becomes inoperative (e.g. QET VOR in MMQT as required for the special engine-out DP); [landing data] would then have to generate numbers that allow for a straight out climb not requiring the NAVAID which would have crews flying straight into terrain.If flying a special DP in mountainous terrain is mandatory for terrain clearance; [landing data] should not allow for an option to fly a straight-out engine out departure.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.