Narrative:

I was on a right downwind for vny runway 16R. There was a citation ahead; higher; and outside of me; on the turbine aircraft right downwind for runway 16R. There were other aircraft in both the right pattern for runway 16R and the left pattern for runway 16L. When I was abeam the control tower; it became apparent that the tower was no longer talking on the radio. I could hear the xmissions of other aircraft; but no response from the tower. Also; there were no light signals from the tower. As I continued downwind; there was a brief radio transmission from the tower clearing me to land. After I landed; I was cleared to cross runway 16L; and to contact ground control. When I called ground; there was no response; and no light signal. After waiting over 5 mins; I taxied to parking. Later I heard that the tower had suffered a power failure. Towers must have back-up system that are immediately available; even if they are only hand-held radios; while radio problems; or power problems that preclude light signals; are being diagnosed and corrected. All of the aircraft approaching van nuys were in limbo: was the tower OTS; so that the airport was no longer controled; and uncontrolled airport procedures should be employed; or was the tower's inability communicate only very temporary; and in a few seconds; would be corrected. If some of the aircraft had decided to use uncontrolled airport procedures to complete their lndgs; while other aircraft had decided to await the resumption of tower communications and to continue downwind; there could have been collisions between aircraft.

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Original NASA ASRS Text

Title: SMA ON DOWNWIND TO VNY DESCRIBED APPARENT TWR PWR FAILURE RESULTING IN INTERMITTENT RADIO COM WITH ATC.

Narrative: I WAS ON A R DOWNWIND FOR VNY RWY 16R. THERE WAS A CITATION AHEAD; HIGHER; AND OUTSIDE OF ME; ON THE TURBINE ACFT R DOWNWIND FOR RWY 16R. THERE WERE OTHER ACFT IN BOTH THE R PATTERN FOR RWY 16R AND THE L PATTERN FOR RWY 16L. WHEN I WAS ABEAM THE CTL TWR; IT BECAME APPARENT THAT THE TWR WAS NO LONGER TALKING ON THE RADIO. I COULD HEAR THE XMISSIONS OF OTHER ACFT; BUT NO RESPONSE FROM THE TWR. ALSO; THERE WERE NO LIGHT SIGNALS FROM THE TWR. AS I CONTINUED DOWNWIND; THERE WAS A BRIEF RADIO XMISSION FROM THE TWR CLRING ME TO LAND. AFTER I LANDED; I WAS CLRED TO CROSS RWY 16L; AND TO CONTACT GND CTL. WHEN I CALLED GND; THERE WAS NO RESPONSE; AND NO LIGHT SIGNAL. AFTER WAITING OVER 5 MINS; I TAXIED TO PARKING. LATER I HEARD THAT THE TWR HAD SUFFERED A PWR FAILURE. TWRS MUST HAVE BACK-UP SYS THAT ARE IMMEDIATELY AVAILABLE; EVEN IF THEY ARE ONLY HAND-HELD RADIOS; WHILE RADIO PROBS; OR PWR PROBS THAT PRECLUDE LIGHT SIGNALS; ARE BEING DIAGNOSED AND CORRECTED. ALL OF THE ACFT APCHING VAN NUYS WERE IN LIMBO: WAS THE TWR OTS; SO THAT THE ARPT WAS NO LONGER CTLED; AND UNCTLED ARPT PROCS SHOULD BE EMPLOYED; OR WAS THE TWR'S INABILITY COMMUNICATE ONLY VERY TEMPORARY; AND IN A FEW SECONDS; WOULD BE CORRECTED. IF SOME OF THE ACFT HAD DECIDED TO USE UNCTLED ARPT PROCS TO COMPLETE THEIR LNDGS; WHILE OTHER ACFT HAD DECIDED TO AWAIT THE RESUMPTION OF TWR COMS AND TO CONTINUE DOWNWIND; THERE COULD HAVE BEEN COLLISIONS BTWN ACFT.

Data retrieved from NASA's ASRS site as of May 2009 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.