Narrative:

Our clearance route from mdw was via midway 4 departure pll as filed. Simultaneous departures were in effect off runways 4 and 31. I anticipated receiving runway 31 based on our departure direction and focused on that section of the departure after receiving the clearance. After contacting ground for taxi close to two hours later we received runway 4R. During the taxi before takeoff briefing I reviewed the briefing for runway 4 which reads 'northbound departures assigned heading 360 degrees clockwise thru 080 turn right; climb on heading 100 until leaving 2400; then via vector to assigned route.' unaware of our departure heading but expecting it to fall in the area specified I briefed that we would fly the 100 degree heading until 2400 ft then assigned heading; not paying attention to the actual headings specified in the departure. After being cleared for takeoff we were assigned a left turn heading 250 degrees. I asked my copilot if we should still turn right via the departure which he incorrectly relayed to the controller asking if it was a right turn or left turn to heading 250 degrees. The controller restated left turn to 250 degree heading. I understood that it was a left turn to 250 degrees but I still thought that we needed to conduct the departure requiring the right turn first and stated this the my copilot. On departure I did initiate a turn to the right at which time the controller stated again that we were cleared for a left turn and to immediately turn left and keep it tight; at which we complied. There were no further incidents or unusual actions. I think my confusion came from the fact that there is nothing else stated on the departure if you are flying a heading other than the northbound headings off runway 4L and right. I think this is the reason that in my brief I perceived the right turn as my only departure option. If the chart read 'all others fly assigned heading;' I think I would have been more aware whether our heading was inside the northbound departure headings or not. As is; the departure has no information or direction for departing aircraft using this SID off runway 4 until the tower gives it to you as you receive your takeoff clearance. It leaves me with an uneasy feeling holding short of a runway that I have never departed before and having no idea what to expect. The problem would have been avoided had we successfully communicated our confusion regarding the requirement for the right turn via the departure.callback conversation with reporter revealed the following information: reporter stated that while en route to the flight's destination the crew studied the SID and discovered that the aircraft should have been turned to heading 250 degrees within 4 NM after takeoff. However; the SID's initial climb statement 'take-off runways 4/right:.....' led them to believe when departing north bound they should turn to heading 100 degrees before turning to heading 250 degrees. The controller's instruction to turn immediately to 250 degrees redirected their thinking and made them realize their error. However; the reporter believes that a SID wording change could correct misunderstandings.

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Original NASA ASRS Text

Title: A PILOT DEPARTING ON THE MIDWAY 4 SID RWY 4 EXPERIENCED CONFUSION ABOUT AN ASSIGNED HDG OUTSIDE THE 360 DEGS - 080 DEGS AND TURNED TO 100 DEGS INSTEAD OF 250 DEGS.

Narrative: OUR CLEARANCE ROUTE FROM MDW WAS VIA MIDWAY 4 DEPARTURE PLL AS FILED. SIMULTANEOUS DEPARTURES WERE IN EFFECT OFF RWYS 4 AND 31. I ANTICIPATED RECEIVING RWY 31 BASED ON OUR DEPARTURE DIRECTION AND FOCUSED ON THAT SECTION OF THE DEPARTURE AFTER RECEIVING THE CLEARANCE. AFTER CONTACTING GROUND FOR TAXI CLOSE TO TWO HOURS LATER WE RECEIVED RWY 4R. DURING THE TAXI BEFORE TAKEOFF BRIEFING I REVIEWED THE BRIEFING FOR RWY 4 WHICH READS 'NORTHBOUND DEPARTURES ASSIGNED HEADING 360 DEGS CLOCKWISE THRU 080 TURN RIGHT; CLIMB ON HEADING 100 UNTIL LEAVING 2400; THEN VIA VECTOR TO ASSIGNED ROUTE.' UNAWARE OF OUR DEPARTURE HEADING BUT EXPECTING IT TO FALL IN THE AREA SPECIFIED I BRIEFED THAT WE WOULD FLY THE 100 DEG HEADING UNTIL 2400 FT THEN ASSIGNED HEADING; NOT PAYING ATTENTION TO THE ACTUAL HEADINGS SPECIFIED IN THE DEPARTURE. AFTER BEING CLEARED FOR TAKEOFF WE WERE ASSIGNED A LEFT TURN HEADING 250 DEGS. I ASKED MY COPILOT IF WE SHOULD STILL TURN RIGHT VIA THE DEPARTURE WHICH HE INCORRECTLY RELAYED TO THE CONTROLLER ASKING IF IT WAS A RIGHT TURN OR LEFT TURN TO HEADING 250 DEGS. THE CONTROLLER RESTATED LEFT TURN TO 250 DEG HEADING. I UNDERSTOOD THAT IT WAS A LEFT TURN TO 250 DEGS BUT I STILL THOUGHT THAT WE NEEDED TO CONDUCT THE DEPARTURE REQUIRING THE RIGHT TURN FIRST AND STATED THIS THE MY COPILOT. ON DEPARTURE I DID INITIATE A TURN TO THE RIGHT AT WHICH TIME THE CONTROLLER STATED AGAIN THAT WE WERE CLEARED FOR A LEFT TURN AND TO IMMEDIATELY TURN LEFT AND KEEP IT TIGHT; AT WHICH WE COMPLIED. THERE WERE NO FURTHER INCIDENTS OR UNUSUAL ACTIONS. I THINK MY CONFUSION CAME FROM THE FACT THAT THERE IS NOTHING ELSE STATED ON THE DEPARTURE IF YOU ARE FLYING A HEADING OTHER THAN THE NORTHBOUND HEADINGS OFF RWY 4L AND R. I THINK THIS IS THE REASON THAT IN MY BRIEF I PERCEIVED THE RIGHT TURN AS MY ONLY DEPARTURE OPTION. IF THE CHART READ 'ALL OTHERS FLY ASSIGNED HEADING;' I THINK I WOULD HAVE BEEN MORE AWARE WHETHER OUR HEADING WAS INSIDE THE NORTHBOUND DEPARTURE HEADINGS OR NOT. AS IS; THE DEPARTURE HAS NO INFORMATION OR DIRECTION FOR DEPARTING AIRCRAFT USING THIS SID OFF RWY 4 UNTIL THE TOWER GIVES IT TO YOU AS YOU RECEIVE YOUR TAKEOFF CLEARANCE. IT LEAVES ME WITH AN UNEASY FEELING HOLDING SHORT OF A RUNWAY THAT I HAVE NEVER DEPARTED BEFORE AND HAVING NO IDEA WHAT TO EXPECT. THE PROBLEM WOULD HAVE BEEN AVOIDED HAD WE SUCCESSFULLY COMMUNICATED OUR CONFUSION REGARDING THE REQUIREMENT FOR THE RIGHT TURN VIA THE DEPARTURE.CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: REPORTER STATED THAT WHILE ENRTE TO THE FLT'S DESTINATION THE CREW STUDIED THE SID AND DISCOVERED THAT THE ACFT SHOULD HAVE BEEN TURNED TO HDG 250 DEGS WITHIN 4 NM AFTER TKOF. HOWEVER; THE SID'S INITIAL CLIMB STATEMENT 'TAKE-OFF RUNWAYS 4/R:.....' LED THEM TO BELIEVE WHEN DEPARTING NORTH BOUND THEY SHOULD TURN TO HDG 100 DEGS BEFORE TURNING TO HDG 250 DEGS. THE CTLR'S INSTRUCTION TO TURN IMMEDIATELY TO 250 DEGS REDIRECTED THEIR THINKING AND MADE THEM REALIZE THEIR ERROR. HOWEVER; THE REPORTER BELIEVES THAT A SID WORDING CHANGE COULD CORRECT MISUNDERSTANDINGS.

Data retrieved from NASA's ASRS site as of January 2009 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.