Air carrier flight crew reported that; due to confusing communications with tower while receiving an...

Attributes
ACN	1544139
Time
Date	201805
Local Time Of Day	0601-1200
Place
Locale Reference	MDW.Airport
State Reference	IL
Environment
Light	Daylight
Aircraft 1
Make Model Name	Large Transport Low Wing 2 Turbojet Eng
Operating Under FAR Part	Part 121
Flight Phase	Takeoff
Flight Plan	IFR
Person 1
Function	Pilot Not Flying First Officer
Qualification	Flight Crew Air Transport Pilot (ATP) Flight Crew Instrument Flight Crew Multiengine
Experience	Flight Crew Last 90 Days 94 Flight Crew Type 291
Person 2
Function	Pilot Flying Captain
Qualification	Flight Crew Instrument Flight Crew Air Transport Pilot (ATP) Flight Crew Multiengine
Experience	Flight Crew Last 90 Days 528
Events
Anomaly	Deviation - Procedural Clearance Deviation - Track / Heading All Types

Narrative:

Taxiing for takeoff on runway 4R; tower asked if we were ready to take off [runway] 4R. We said 'yes'. Tower said 'after this aircraft lands; be ready to go.' I said 'roger'. Tower said 'line up and wait 4R.' I said 'line up and wait on 4R.' taxiing past the hold short line on runway 4R; tower said 'come up on power.' I thought tower said 'come up on tower.' I told tower 'we are up on tower.' tower said again 'come up on power.' I again said 'we are on tower.' after I said that a second time; my captain said 'tower said come up on power.' at that point we were almost lined up on [runway] 4R. Another aircraft said 'tower is saying bring up the thrust.' at that point; the aircraft that just landed turned off and tower cleared us to take off on [runway] 4R and turn left to 250. Not sure if I read back cleared for takeoff on [runway] 4R and turn right to 150; or the correct clearance of left turn to 250. But I did put in 150 in the heading selector. We took off; and at 400 feet AGL we turned right to 150. Around 1000 feet; tower came on and said it was a left turn to 250. Tower then again gave us a new heading and no further problems after that.

Original NASA ASRS Text

Title: Air carrier flight crew reported that; due to confusing communications with Tower while receiving an expedited takeoff clearance; they misunderstood the ATC-issued heading clearance to fly after takeoff.

Narrative: Taxiing for takeoff on Runway 4R; Tower asked if we were ready to take off [Runway] 4R. We said 'yes'. Tower said 'after this aircraft lands; be ready to go.' I said 'roger'. Tower said 'line up and wait 4R.' I said 'line up and wait on 4R.' Taxiing past the hold short line on Runway 4R; Tower said 'come up on power.' I thought Tower said 'come up on Tower.' I told Tower 'we are up on Tower.' Tower said again 'come up on power.' I again said 'we are on Tower.' After I said that a second time; my Captain said 'Tower said come up on power.' At that point we were almost lined up on [Runway] 4R. Another aircraft said 'Tower is saying bring up the thrust.' At that point; the aircraft that just landed turned off and Tower cleared us to take off on [Runway] 4R and turn left to 250. Not sure if I read back cleared for takeoff on [Runway] 4R and turn right to 150; or the correct clearance of left turn to 250. But I did put in 150 in the heading selector. We took off; and at 400 feet AGL we turned right to 150. Around 1000 feet; Tower came on and said it was a left turn to 250. Tower then again gave us a new heading and no further problems after that.

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.

Air carrier flight crew reported that; due to confusing communications with tower while receiving an expedited takeoff clearance; they misunderstood the ATC-issued heading clearance to fly after takeoff.