An air carrier crew may have taxied onto a runway without clearance at MMMX.

Attributes
ACN	258799
Time
Date	199312
Day	Thu
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : mmmx
State Reference	FO
Altitude	agl bound lower : 0 agl bound upper : 0
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Operator	common carrier : air carrier
Make Model Name	Large Transport, Low Wing, 2 Turbojet Eng
Navigation In Use	Other Other
Flight Phase	ground other : taxi
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : instrument pilot : atp pilot : commercial
Experience	flight time last 90 days : 150 flight time total : 7000 flight time type : 1200
ASRS Report	258799
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 60 flight time total : 13000 flight time type : 60
ASRS Report	258666
Events
Anomaly	incursion : runway non adherence : clearance other anomaly other
Independent Detector	other controllera
Resolutory Action	controller : issued new clearance other
Consequence	Other
Supplementary
Air Traffic Incident	Pilot Deviation
Situations
ATC Facility	procedure or policy : unspecified
Airport	other physical facility

Narrative:

Air carrier 1 flight landed MMMX on runway 5R. We exited runway 5R, left onto taxiway east to hold short of runway 5L. Tower on 118.1 cleared to cross runway 5L and contact ground control on 121.0. Ground cleared us on taxiway B then into taxiway C then back to taxiway B (there were many construction areas on the ramp). As we were almost past B7, ground asked us to make a left turn onto B7 and then back-taxi on runway 5L to get to gate X. We made a very sharp turn onto B7. As we approached runway 5L, there was an air carrier 2 swbound (taxiing) on runway 5L, just past E2. There were 2 air carrier aircraft crossing runway 5L at B3 (off to our right). We turned right on runway 5L and proceeded southwest to taxiway B6. When we were almost to B6, ground control said 'air carrier 1, you were not cleared on the runway, you are now cleared on the runway, exit at the next taxiway.' we continued to gate X without any problems. Since we were the only aircraft that ground control was issuing instructions to in english, we were not able to determine what other aircraft were being instructed. The difficulty in understanding ground control's english and the busy frequency (mostly in spanish) made this difficult at best.

Original NASA ASRS Text

Title: AN ACR CREW MAY HAVE TAXIED ONTO A RWY WITHOUT CLRNC AT MMMX.

Narrative: ACR 1 FLT LANDED MMMX ON RWY 5R. WE EXITED RWY 5R, L ONTO TXWY E TO HOLD SHORT OF RWY 5L. TWR ON 118.1 CLRED TO CROSS RWY 5L AND CONTACT GND CTL ON 121.0. GND CLRED US ON TXWY B THEN INTO TXWY C THEN BACK TO TXWY B (THERE WERE MANY CONSTRUCTION AREAS ON THE RAMP). AS WE WERE ALMOST PAST B7, GND ASKED US TO MAKE A L TURN ONTO B7 AND THEN BACK-TAXI ON RWY 5L TO GET TO GATE X. WE MADE A VERY SHARP TURN ONTO B7. AS WE APCHED RWY 5L, THERE WAS AN ACR 2 SWBOUND (TAXIING) ON RWY 5L, JUST PAST E2. THERE WERE 2 ACR ACFT XING RWY 5L AT B3 (OFF TO OUR R). WE TURNED R ON RWY 5L AND PROCEEDED SW TO TXWY B6. WHEN WE WERE ALMOST TO B6, GND CTL SAID 'ACR 1, YOU WERE NOT CLRED ON THE RWY, YOU ARE NOW CLRED ON THE RWY, EXIT AT THE NEXT TXWY.' WE CONTINUED TO GATE X WITHOUT ANY PROBS. SINCE WE WERE THE ONLY ACFT THAT GND CTL WAS ISSUING INSTRUCTIONS TO IN ENGLISH, WE WERE NOT ABLE TO DETERMINE WHAT OTHER ACFT WERE BEING INSTRUCTED. THE DIFFICULTY IN UNDERSTANDING GND CTL'S ENGLISH AND THE BUSY FREQ (MOSTLY IN SPANISH) MADE THIS DIFFICULT AT BEST.

Data retrieved from NASA's ASRS site as of July 2007 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.