Learjet 35
Flight Crew Air Transport Pilot (ATP)
Communication Breakdown
ATC Issue All Types; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy
Air Traffic Control Issued Advisory / Alert; Flight Crew Became Reoriented
Human Factors; Procedure
We departed when the airport control tower was not in operation.  The non flying pilot received an IFR clearance via a phone call to SoCal approach After departure; on our first communication to departure; ATC questioned us about our flight status.  ATC asked if we departed VFR.  The pilot monitoring had responded that we had departed IFR.  ATC responded that we did not receive clearance to depart IFR and must have departed VFR.  After this short conversation with ATC at the time no further action was taken and we continued our flight as planned. The pilot monitoring stated while receiving clearance for our flight he had not received any instructions to 'hold for release' or a 'clearance void time'.  The pilot monitoring simply received an IFR clearance without any restrictions. PIC needs to verify clearance on the ground.  If a clearance void time has not been given a return call to the controlling ATC facility must occur to verify we do in fact have a current valid IFR clearance to depart.
I obtained IFR clearance via the phone prior to start up. We taxied out for departure and took off and called approach in the air. SoCal questioned us about our flight status asking if we were VFR or IFR. I responded that we had departed IFR and that we were climbing to our assigned altitude. Approach said we had not received IFR clearance so we must have departed VFR. After this initial questioning; no further conversation concerning the clearance took place and we continued the flight as planned. While receiving IFR clearance; I was not given a 'void time;' a 'hold for release;' or any instruction to contact approach prior to departure for further clearance. Both pilots should discuss the retrieved clearance from ATC to make sure no errors in the field plan were found and to also make sure all required information has been obtained necessary for departure.
Learjet 35 flight crew reports receiving an IFR clearance via phone for an early AM departure; prior to engine start; and departing. ATC questions the crew about their clearance status; stating that they must be VFR because they are not IFR.