Narrative:

We were cleared to taxi to runway 31C via txwys papa and golf at midway airport. On taxiway golf behind a B727 we requested a left turn onto taxiway kilo to be in position to comply with departure clearance time of xa:59 mins past the hour. Ground control denied our request and at the same time the B727 taxied forward and made a 90 degree right turn onto taxiway echo 3 to hold short of runway 31C. Now it was possible, we thought, to approach the hold short line for runway 31C by taxiing behind the B727 and making a right turn onto taxiway echo 2. This is a common procedure at midway airport. The captain taxied behind the B727 and it appeared to me that we would cross into the runway 31R protected area with our left wingtip. Since I had seen this procedure before at midway, and it was later confirmed by the tower that this procedure occurs, I did not speak up. As the captain made the right turn onto 'echo 2' it became evident that he could not taxi forward and maintain a safe distance from the B727 on 'echo 3,' as a result he stopped the aircraft. At that time I spoke up and stated that I felt we were possibly across the runway 31R hold short line. The captain said he did not think we were, shortly thereafter, the tower notified us that we made a left turn and crossed into runway 31R. The captain had veered to the left to clear the B727 as we taxied behind it. The tower saw this as a left turn. The captain confused this with the left turn that was denied us by ground control. The captain had complied with ground control by not turning left onto 'kilo' as a result there was confusion over the 2 left turns. A telephone call to the tower resolved the situation. The cause of this problem is 2-FOLD: no 1: lack of space at midway airport. The clearway for runway 31R causes a trapezoidal hold short area for both runway 31R and runway 31C with the narrow end of the trapezoid at the treshold of runway 31C. Runway 31C is the main runway for midway and all major airlines approach runway 31C from either 'golf' or 'echo'. There are 3 parallel taxiway centerlines in this hold short area noted as 'echo 1,2 and 3.' traffic is routed on all 3 txwys to accommodate as many aircraft as possible. As a result, it is common, again acknowledged by ATC, for aircraft to pass behind other aircraft on 'echo 3' to hold short on echo 2 which may temporarily cause a runway 31R incursion into the clearway at least 100 ft prior to the runway 31R threshold. There are no notes or instructions regarding which aircraft can be accomodated side by side on echo 1,2 and 3 or which aircraft will fit on these txwys between runway 31C and runway 31R hold short lines. All aircraft have been in all position. No 2: the crew's anticipation of a departure clearance time. It was 'wheels up' time as we taxied behind the B727 trying to be in position at the proper time and not lose our slot. Combined with the observed practice of taxiing behind 'echo 3' aircraft and not realizing the clearance limitations for aircraft side by side on 'echo 2 and 3', this could have become a safety issue for aircraft approaching runway 31R. The solution includes: 1) a more assertive statement by the first officer as soon as it appeared that there may have been a runway 31R conflict combined with a radio call to ATC to coordinate action. 2) more importantly, notes on the midway airport diagram that spells out which aircraft can be accommodated at what times. For example, during IFR operations with runway 31R not in use, it is acceptable for aircraft to await runway 31C departures while intruding into runway 31R without specific ATC authorization. 3) when in doubt as to the required clearance from any object, stop and verify the appropriate action as necessary with the appropriate facility.

Related reports:

Google
 

Original NASA ASRS Text

Title: B757 CREW ENCOUNTERED CONFUSING HOLD SHORT MARKINGS FOR RWY 31C AND RWY 31R IN THE TXWY ECHO AREA AT MDW.

Narrative: WE WERE CLRED TO TAXI TO RWY 31C VIA TXWYS PAPA AND GOLF AT MIDWAY ARPT. ON TXWY GOLF BEHIND A B727 WE REQUESTED A L TURN ONTO TXWY KILO TO BE IN POS TO COMPLY WITH DEP CLRNC TIME OF XA:59 MINS PAST THE HOUR. GND CTL DENIED OUR REQUEST AND AT THE SAME TIME THE B727 TAXIED FORWARD AND MADE A 90 DEGREE R TURN ONTO TXWY ECHO 3 TO HOLD SHORT OF RWY 31C. NOW IT WAS POSSIBLE, WE THOUGHT, TO APCH THE HOLD SHORT LINE FOR RWY 31C BY TAXIING BEHIND THE B727 AND MAKING A R TURN ONTO TXWY ECHO 2. THIS IS A COMMON PROC AT MIDWAY ARPT. THE CAPT TAXIED BEHIND THE B727 AND IT APPEARED TO ME THAT WE WOULD CROSS INTO THE RWY 31R PROTECTED AREA WITH OUR L WINGTIP. SINCE I HAD SEEN THIS PROC BEFORE AT MIDWAY, AND IT WAS LATER CONFIRMED BY THE TWR THAT THIS PROC OCCURS, I DID NOT SPEAK UP. AS THE CAPT MADE THE R TURN ONTO 'ECHO 2' IT BECAME EVIDENT THAT HE COULD NOT TAXI FORWARD AND MAINTAIN A SAFE DISTANCE FROM THE B727 ON 'ECHO 3,' AS A RESULT HE STOPPED THE ACFT. AT THAT TIME I SPOKE UP AND STATED THAT I FELT WE WERE POSSIBLY ACROSS THE RWY 31R HOLD SHORT LINE. THE CAPT SAID HE DID NOT THINK WE WERE, SHORTLY THEREAFTER, THE TWR NOTIFIED US THAT WE MADE A L TURN AND CROSSED INTO RWY 31R. THE CAPT HAD VEERED TO THE L TO CLEAR THE B727 AS WE TAXIED BEHIND IT. THE TWR SAW THIS AS A L TURN. THE CAPT CONFUSED THIS WITH THE L TURN THAT WAS DENIED US BY GND CTL. THE CAPT HAD COMPLIED WITH GND CTL BY NOT TURNING L ONTO 'KILO' AS A RESULT THERE WAS CONFUSION OVER THE 2 L TURNS. A TELEPHONE CALL TO THE TWR RESOLVED THE SIT. THE CAUSE OF THIS PROB IS 2-FOLD: NO 1: LACK OF SPACE AT MIDWAY ARPT. THE CLEARWAY FOR RWY 31R CAUSES A TRAPEZOIDAL HOLD SHORT AREA FOR BOTH RWY 31R AND RWY 31C WITH THE NARROW END OF THE TRAPEZOID AT THE TRESHOLD OF RWY 31C. RWY 31C IS THE MAIN RWY FOR MIDWAY AND ALL MAJOR AIRLINES APCH RWY 31C FROM EITHER 'GOLF' OR 'ECHO'. THERE ARE 3 PARALLEL TXWY CENTERLINES IN THIS HOLD SHORT AREA NOTED AS 'ECHO 1,2 AND 3.' TFC IS ROUTED ON ALL 3 TXWYS TO ACCOMMODATE AS MANY ACFT AS POSSIBLE. AS A RESULT, IT IS COMMON, AGAIN ACKNOWLEDGED BY ATC, FOR ACFT TO PASS BEHIND OTHER ACFT ON 'ECHO 3' TO HOLD SHORT ON ECHO 2 WHICH MAY TEMPORARILY CAUSE A RWY 31R INCURSION INTO THE CLEARWAY AT LEAST 100 FT PRIOR TO THE RWY 31R THRESHOLD. THERE ARE NO NOTES OR INSTRUCTIONS REGARDING WHICH ACFT CAN BE ACCOMODATED SIDE BY SIDE ON ECHO 1,2 AND 3 OR WHICH ACFT WILL FIT ON THESE TXWYS BTWN RWY 31C AND RWY 31R HOLD SHORT LINES. ALL ACFT HAVE BEEN IN ALL POS. NO 2: THE CREW'S ANTICIPATION OF A DEP CLRNC TIME. IT WAS 'WHEELS UP' TIME AS WE TAXIED BEHIND THE B727 TRYING TO BE IN POS AT THE PROPER TIME AND NOT LOSE OUR SLOT. COMBINED WITH THE OBSERVED PRACTICE OF TAXIING BEHIND 'ECHO 3' ACFT AND NOT REALIZING THE CLRNC LIMITATIONS FOR ACFT SIDE BY SIDE ON 'ECHO 2 AND 3', THIS COULD HAVE BECOME A SAFETY ISSUE FOR ACFT APCHING RWY 31R. THE SOLUTION INCLUDES: 1) A MORE ASSERTIVE STATEMENT BY THE FO AS SOON AS IT APPEARED THAT THERE MAY HAVE BEEN A RWY 31R CONFLICT COMBINED WITH A RADIO CALL TO ATC TO COORDINATE ACTION. 2) MORE IMPORTANTLY, NOTES ON THE MIDWAY ARPT DIAGRAM THAT SPELLS OUT WHICH ACFT CAN BE ACCOMMODATED AT WHAT TIMES. FOR EXAMPLE, DURING IFR OPS WITH RWY 31R NOT IN USE, IT IS ACCEPTABLE FOR ACFT TO AWAIT RWY 31C DEPS WHILE INTRUDING INTO RWY 31R WITHOUT SPECIFIC ATC AUTHORIZATION. 3) WHEN IN DOUBT AS TO THE REQUIRED CLRNC FROM ANY OBJECT, STOP AND VERIFY THE APPROPRIATE ACTION AS NECESSARY WITH THE APPROPRIATE FAC.

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.