Bonanza 35
Flight Crew Instrument; Flight Crew Private
Flight Crew Last 90 Days 5; Flight Crew Total 450; Flight Crew Type 200
Communication Breakdown; Situational Awareness
ATC Issue All Types; Deviation / Discrepancy - Procedural FAR; Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter CFTT / CFIT
Air Traffic Control Issued New Clearance
Procedure; Airspace Structure
I was on left downwind for ZZZ preparing for the landing. I crossed the point abeam the threshold; lowered my gear and started my descent. The tower called for helicopter traffic nearby. I reported negative traffic and tower instructed to extend downwind and that they would call my base. I complied and continued still slightly descending; expecting to get on the base turn any second.However the controller either got busy with other traffic and forgot about me or decided to re-sequence me for landing. I continued on downwind; but stopped my descent and was holding altitude (at that point it was around 1200 MSL; 300 feet below TPA). After being on downwind until about 3nm from the airport I realized that I was too low because of rising terrain which should be about 600 feet MSL at that point; so I was probably flying about 500-600 feet above the houses; and even higher terrain was ahead of me. At that point I added power and raised my gear in order to achieve a good climb rate. The tower finally called my base about 4.5nm from the airport; and the rest of the flight was uneventful.In retrospect I should have stopped my descent earlier and started my climb as soon as I was beyond normal point when I turn base which is my normal practice when dealing with extended downwind. I think the contributing factor in this case was the anticipation of imminent base turn because I was vectored around much slower helicopter traffic and not some jet on instrument approach which is usually the case for extended downwind; plus not flying much recently also affected my decision making. Also; the normal pattern is right traffic which doesn't put you over rising terrain that quickly.Overall it wasn't a dangerous situation; but it could be if it happened at night; plus I got lower than prescribed by FAR over populated area (although as this was a part of landing procedure; not sure if it applies even though the downwind extended too much).
BE35 pilot reported descending too low waiting for ATC to call the base turn due to traffic.