Date: 201406
Local time of day: 1201-1800
Location: ZZZ.TRACON, US
Flight conditions: VMC
Light: Daylight
Aircraft: B737-300
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Descent
Airspace: Class B ZZZ; Class E ZZZ
ATC / advisory: TRACON ZZZ; Tower ZZZ
Aircraft component: Tablet
Component problem: Improperly Operated
Reporter organization: Air Carrier
Reporter function: Pilot Not Flying; First Officer
Human factors: Confusion; Distraction; Human-Machine Interface; Situational Awareness; Workload
Second reporter function: Captain; Pilot Flying
Anomaly: Aircraft Equipment Problem Less Severe; Deviation - Altitude Overshoot; Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural Clearance; Flight Deck / Cabin / Aircraft Event Other / Unknown
Detector: Person Flight Crew
When detected: In-flight
Result: Flight Crew Returned To Clearance; Flight Crew Took Evasive Action; Flight Crew Became Reoriented; Flight Crew Overcame Equipment Problem
Contributing factors: Human Factors; Chart Or Publication; Procedure; Aircraft
Primary problem: Ambiguous

Narrative: During a very busy arrival on the RNAV with multiple ATC changes in route/altitude/speed restrictions; the iPad gave 'Battery at 10%' message.  I elected not to revert to paper publications for two primary reasons: (1) I reasoned the battery would be sufficient to finish the flight; and (2) the arrival had been extremely busy with multiple changes to the 'descend via' clearance on the RNAV Arrival; so I felt it was better to be 'in the loop' monitoring the pilot flying and handling radios.  The first approach to Runway XXL resulted in a go-around.  While being vectored downwind for the second approach; the iPad powered down (OFF).  We completed the approach; landing; and taxi to the gate without publications on my side (First Officer side).  The Captain had full use of his iPad.  There was an FAA Evaluator on board who noticed and commented on the fact that the iPad had powered down prior to landing and that we had to taxi without the use of the First Officer's iPad. Preventative Measures: (1) Place iPad charging system in aircraft. (2) Follow Company procedures to revert to paper publications when battery charge is low. (3) Be cognizant of battery level at all times and extract backup paper publications during non-dynamic flight periods (cruise) if there is any possibility that the iPad battery will expire.


Second narrative: Cleared the RNAV and 'descend via.' Multiple changes on the way in. Different speeds and altitudes; each one reprogrammed in the FMS correctly. One mile prior to and while descending to waypoint constraint; the autopilot did not level at 9;000 feet. It was 8;800 feet and then I took control and corrected back to 9;000 feet. There was no mention or conflict from ATC; however; there was a Fed on the jumpseat.The only thing I can think of is that because of all the changes to clearances; the FMS was still computing and didn't level.


Synopsis: While on a very busy RNAV arrival with multiple speed and altitude changes; a B737-300 Captain manually returned to the 9;000 FT constraint after the FMS failed to level. During the descent; the First Officer's iPad alerted 'Battery at 10%' and then auto-shut down during a second visual approach following a go-around.