Early on a saturday morning, just before the tower at DVT opened (0545 Local), my CFI and I were holding short of Runway 7R, just about to announce our intentions to take the runway for an east departure for an instrument training flight. I made the call, "Deer Valley Traffic, Cessna 104 taking runway seven-right, straight out departure, deer valley traffic." Onto the runway, lights, camera action, and we were at full power. As I looked up from my engine and panel check, a pair of white lights appeared at the end of the runway that didn't seem to belong...my instructor let loose, "Pull off the runway, NOW!" before I could register the source of the unusual lights... we pulled to the right side of the runway and high-tailed it to the first available taxi-way. The opposing aircraft was airborne, abeam our position as we pulled off the runway. We stopped off the runway, and watched the twin climb into the night sky. My instructor meanwhile made calls for the aircraft departing for a call sign. Radio silence. He contacted the tower to see if they had read any of the twin's transmissions. Negative. My instructor, being a free-lancer and having just completed a stint as a CFI employee at the local professional flight school, contacted dispatch on our radio and requested the tail number and pilot flying the twin that had just departed. It was an aircraft from his former flight school, piloted by a CFI that he knows.
Needless to say, we sat there shaking for about 15 minutes before we felt comfortable enough to continue our lesson. We completed our training flight without further incident.
Following the flight, my instructor found the pilot cfi of the offending aircraft at the FBO and confronted him about the incident. The CFI resopnded that he had "not even seen" our aircraft--despite that all our lights were on at that point (landing, nav, strobes, beacon). My CFI called the tower to see if they had happened to record any of the calls on frequency. They had, and we were invited to come by and listen. My call was clear and concise (the chief controller who was helping us complimented my phraseology!), and just 13 seconds after my call, a garbled 3-letter N number was called with no further information, rendering the call useless and completely unreadable. The other pilot was not cited for a runway incursion because the tower was not yet in operation at the time of the incident.
My takeaway from the incident is this...always, without fail, always check your runway for obstacles, including other aircraft. Do Not rely on the radios to indicate other traffic operating at the airfield, and take due caution when assessing the appropriate runway for use. Just because the runway in use is X, doesn't mean that some yahoo won't try to use runway Y. Be safe, and fly your best.