A B747 flight crew reported turning toward terrain on a night approach to MMMX when they apparently ...

Attributes
ACN	1291207
Time
Date	201508
Local Time Of Day	0001-0600
Place
Locale Reference	MMMX.Airport
State Reference	FO
Environment
Flight Conditions	VMC
Light	Night
Aircraft 1
Make Model Name	B747 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Flight Phase	Initial Approach
Route In Use	Vectors
Flight Plan	IFR
Person 1
Function	Check Pilot Captain
Qualification	Flight Crew Air Transport Pilot (ATP)
Person 2
Function	Relief Pilot First Officer Pilot Not Flying
Qualification	Flight Crew Commercial
Events
Anomaly	ATC Issue All Types Deviation - Procedural Clearance Deviation - Track / Heading All Types

Narrative:

Approach ILS runway 05R mex flight conditions night. Approaching position mavek aircraft was configured at flaps 20 degrees and crossing mavek configured gear down and flaps 25 (planning for 30 degrees) for descent from 12;000 to the next altitude of 8;800 feet for the interception of final approach to runway 05R. Upon crossing mavek we thought we were given a heading of 250 to fly due to closeness behind traffic ahead. I selected heading select and made the turn thinking this was a small widening vector for a subsequent turn to intercept final; but was concerned for terrain. Controller promptly asked what we were doing and we clarified what we thought was our assigned heading. He then gave us a right turn to 360 and a climb to 14;000 feet and then 15;000 feet. We cleaned up the aircraft to flaps 10 and re-inserted mavek into the FMC for a subsequent descent to 12;000 and the arrival for runway 05R. The arrival was subsequently flown with no further event. Listen and confirm all instructions; controller was very busy.

Original NASA ASRS Text

Title: A B747 flight crew reported turning toward terrain on a night approach to MMMX when they apparently misunderstood an ATC clearance.

Narrative: Approach ILS RWY 05R MEX Flight conditions night. Approaching position MAVEK aircraft was configured at flaps 20 degrees and crossing MAVEK configured gear down and flaps 25 (planning for 30 degrees) for descent from 12;000 to the next altitude of 8;800 feet for the interception of final approach to runway 05R. Upon crossing MAVEK we thought we were given a heading of 250 to fly due to closeness behind traffic ahead. I selected HDG Select and made the turn thinking this was a small widening vector for a subsequent turn to intercept final; but was concerned for terrain. Controller promptly asked what we were doing and we clarified what we thought was our assigned heading. He then gave us a right turn to 360 and a climb to 14;000 feet and then 15;000 feet. We cleaned up the aircraft to flaps 10 and re-inserted MAVEK into the FMC for a subsequent descent to 12;000 and the arrival for runway 05R. The arrival was subsequently flown with no further event. Listen and confirm all instructions; Controller was very busy.

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.