Air carrier flight crew reported not making a crossing restriction on the FRNCH3 STAR to den.

Narrative:

This occurred on the second day of a three-day am trip. Both of the two mornings were about (time removed) reports and I hadn't slept a full night before either day. I recall that both the first officer and I were fighting to keep alert on this leg as we began the arrival. The FRNCH3 arrival was briefed as normal; but not very far into the arrival; we were vectored off and given multiple vectors and descents which I complied with using heading select and level change. Finally; we were cleared direct to babaa intersection to rejoin the arrival and to descend via the remainder of the FRNCH3. LNAV was engaged direct to babaa and we set 11;000 feet in the MCP altitude window; as this was the lowest altitude on arrival. However; I failed to reselect VNAV mode; and with the aircraft still in level change; we descended through the babaa restriction of 13;000 feet prior to babaa. At about 12;500 feet and nearly to babaa; approach queried us by asking if we were going to cross babaa at 13;000 feet. I quickly climbed back to up to 13;000 feet but crossed babaa at 12;500 feet; and promptly got the aircraft back into VNAV for the rest of the uneventful arrival and flight.

Original NASA ASRS Text

Title: Air carrier flight crew reported not making a crossing restriction on the FRNCH3 STAR to DEN.

Narrative: This occurred on the second day of a three-day am trip. Both of the two mornings were about (time removed) reports and I hadn't slept a full night before either day. I recall that both the First Officer and I were fighting to keep alert on this leg as we began the arrival. The FRNCH3 Arrival was briefed as normal; but not very far into the arrival; we were vectored off and given multiple vectors and descents which I complied with using Heading Select and Level Change. Finally; we were cleared direct to BABAA intersection to rejoin the arrival and to descend via the remainder of the FRNCH3. LNAV was engaged direct to BABAA and we set 11;000 feet in the MCP altitude window; as this was the lowest altitude on arrival. However; I failed to reselect VNAV mode; and with the aircraft still in Level Change; we descended through the BABAA restriction of 13;000 feet prior to BABAA. At about 12;500 feet and nearly to BABAA; Approach queried us by asking if we were going to cross BABAA at 13;000 feet. I quickly climbed back to up to 13;000 feet but crossed BABAA at 12;500 feet; and promptly got the aircraft back into VNAV for the rest of the uneventful arrival and flight.

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.

Attributes
ACN	1365129
Time
Date	201606
Local Time Of Day	1801-2400
Place
Locale Reference	DEN.Airport
State Reference	CO
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Make Model Name	Large Transport
Operating Under FAR Part	Part 121
Flight Phase	Descent
Route In Use	STAR FRNCH3
Flight Plan	IFR
Person 1
Function	Captain Pilot Flying
Qualification	Flight Crew Air Transport Pilot (ATP)
Experience	Flight Crew Last 90 Days 148
Person 2
Function	First Officer Pilot Not Flying
Qualification	Flight Crew Air Transport Pilot (ATP)
Events
Anomaly	Deviation - Altitude Crossing Restriction Not Met Deviation - Procedural Clearance Deviation - Procedural Published Material / Policy