Super King Air 200
Flight Crew Air Transport Pilot (ATP); Flight Crew Flight Instructor; Flight Crew Multiengine; Flight Crew Instrument
Flight Crew Last 90 Days 80; Flight Crew Total 4000; Flight Crew Type 80
Distraction; Fatigue
Deviation - Altitude Overshoot; Deviation / Discrepancy - Procedural Clearance
Flight Crew Became Reoriented; Flight Crew Overcame Equipment Problem; Flight Crew Returned To Clearance
Aircraft; Environment - Non Weather Related; Human Factors
Climbing out of ELP and passing through around 25;000 feet; My GPS unit flagged an integrity message. At the time of the GPS losing signal; I was direct to INK vor. I reported the failure to ATC (with the understanding that there was a NOTAM for GPS jamming being conducted). The controller gave me a vector direct when able to my destination. As a result of my GPS losing signal the autopilot went into 'roll hold' a basic level that the autopilot defaults to. I placed the autopilot into heading mode and rolled to the assigned heading. What I failed to notice was that the autopilot had also dropped 'altitude select'. This mode is responsible for capturing the assigned altitude. In this case; that altitude was 27;000 feet. I recall acknowledging the altitude alerter at the 1000 feet prior annunciation. However; instead of focusing on the level off I left my attention to resetting the GPS and tuning in frequencies to ground based navigation facilities. As I was looking up a frequency to tune; I noticed the amber light from the altitude alerter was still illuminated. Through all of my previous flying experience I instantly knew that we should have already leveled off. I looked at the altimeter and we were 800 feet higher than our assigned altitude of 27;000 feet. I immediately disengaged the autopilot and corrected to the assigned altitude.Contributing factors include distraction from losing GPS. Fixation while attempting to find other means of navigation; even though the controller gave me an initial vector and I had plenty of time to wait until level off to determine frequencies. In addition; I was approaching the end of my duty day so fatigue may have contributed to my error.
King Air 200 pilot experienced loss of GPS signal after departing ELP and passing through FL250. The failure was due to NOTAMed GPS jamming in the area and ATC assigned a heading to destination. With the loss of NAV capability the autopilot also lost altitude capture; resulting in an 800 foot overshoot of FL270.