Flight Crew Instrument; Flight Crew Multiengine; Flight Crew Private
Flight Crew Last 90 Days 20; Flight Crew Total 3275; Flight Crew Type 2100
Communication Breakdown; Situational Awareness; Training / Qualification
Deviation - Altitude Excursion From Assigned Altitude; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter CFTT / CFIT
Air Traffic Control Provided Assistance; Air Traffic Control Issued Advisory / Alert; Flight Crew Became Reoriented; Flight Crew Took Evasive Action; Flight Crew FLC complied w / Automation / Advisory
Human Factors; Weather; Airspace Structure
On an IFR flight plan; BUR was VMC so I asked for a visual approach. It was hazy and I don't fly into BUR and I couldn't positively identify the airport at 9-10 miles out; and it seemed like SOCAL wanted me to shoot an instrument approach. But I hadn't reviewed the approach plate and I was reluctant to just punch an approach into my Garmin 430W. I was trying to call up the approach on my iPad but it was hot and slow to respond. I prefer to review the approach plates well in advance; memorize the fixes and altitude restrictions. I think the issue was that BUR is near a lot of big hills; so if you don't say you see the airport; and you're relatively high; they want you to shoot an instrument approach. But; as stated; but I hadn't done my normal pre-approach briefing I didn't want to do it. BUR was hard VMC no ceiling and 5-7 miles visibility; as I recall; so I wasn't expecting to do an instrument approach. Twice I went down to 2500 ft; below the 3000 ft assigned. I was in VMC and completely clear of the hills and mountains; but ATC called an altitude alert.  Autopilot apparently was in ATT (Attitude Hold) instead of ALT (Altitude Hold) mode. High stress; due to not being familiar with the approach and not being able to call it up on iPad or iPhone; and didn't apparently switch back to ALT mode after reaching 3000 ft.  I think I'll try to do an approach review for flights into the Los Angeles area regardless of stated conditions. I'm wondering how I could find out in advance about this kind of issue in BUR? It didn't seem that near the mountains.
Piper twin pilot reported descending below an assigned altitude while on an approach to Burbank Airport.