Confusion over the clearance and improper autopilot mode selection led to a possible altitude deviat...

Attributes
ACN	1275667
Time
Date	201507
Local Time Of Day	0601-1200
Place
Locale Reference	IAH.Airport
State Reference	TX
Environment
Flight Conditions	VMC
Light	Dawn
Aircraft 1
Make Model Name	Large Transport Low Wing 2 Turbojet Eng
Operating Under FAR Part	Part 121
Flight Phase	Initial Approach
Route In Use	STAR MSCOT4
Flight Plan	IFR
Component
Aircraft Component	Autoflight System
Person 1
Function	Captain Pilot Not Flying
Qualification	Flight Crew Air Transport Pilot (ATP)
Experience	Flight Crew Last 90 Days 189 Flight Crew Type 5823
Person 2
Function	First Officer Pilot Flying
Qualification	Flight Crew Air Transport Pilot (ATP)
Experience	Flight Crew Last 90 Days 59
Events
Anomaly	Deviation - Altitude Overshoot Deviation - Altitude Crossing Restriction Not Met Deviation - Procedural Clearance Deviation - Procedural FAR Deviation - Procedural Published Material / Policy

Narrative:

We arrived on MSCOT4 arrival. Got clearance from center to descend via. We started the descent via; and got a hand off to approach. Approach told us to descend via the 27 transition for a 26L landing. It took me a couple of calls to clarify what he was asking for; and he eventually just told us to fly a 085 degree heading after domno. The descent went well and in the correct flight mode until after mscot. We ended up in open descent I did not catch the change as I was trying to configure the mcdu for the new arrival clearance. I saw as we were approaching domno that we were descending through 8000ft; the bottom of the arrival window for that fix; and told the PF to level off and climb back to altitude. We got about 400 feet low and climbed quickly back to 8000ft. ATC never mentioned our deviation; and I am not positive that we weren't cleared to 6000ft.

Original NASA ASRS Text

Title: Confusion over the clearance and improper autopilot mode selection led to a possible altitude deviation at DOMNO on the IAH MSCOT4 Arrival. A late runway change from Runway 27 to Runway 26L contributed to the distraction.

Narrative: We arrived on MSCOT4 arrival. Got clearance from center to descend via. We started the descent via; and got a hand off to approach. Approach told us to descend via the 27 transition for a 26L landing. It took me a couple of calls to clarify what he was asking for; and he eventually just told us to fly a 085 degree heading after DOMNO. The descent went well and in the correct flight mode until after MSCOT. We ended up in open descent I did not catch the change as I was trying to configure the MCDU for the new arrival clearance. I saw as we were approaching DOMNO that we were descending through 8000ft; the bottom of the arrival window for that fix; and told the PF to level off and climb back to altitude. We got about 400 feet low and climbed quickly back to 8000ft. ATC never mentioned our deviation; and I am not positive that we weren't cleared to 6000ft.

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.

Confusion over the clearance and improper autopilot mode selection led to a possible altitude deviation at domno on the iah MSCOT4 arrival. A late runway change from runway 27 to runway 26L contributed to the distraction.