Sfo tower controller reported a radio 'dead spot' identified at the approach end of runway 1R that c...

Narrative:

I was working local assist. Aircraft X was instructed to line up and wait on runway 1R. When in position; the local controller attempted to reach aircraft X on the frequency several times; but was unable. This has happened many times before with lower profile jets (smaller citations; lear jets; phenoms; etc). There is apparently a dead spot where the tower antennas do not reach low profile jets while they are in position on runway 1R. The only way to reach them is to relay a message to them through another aircraft. I told the local controller about this and told them that they should tell an air carrier jet who was holding short of runway 1R to instruct aircraft X to move up a few feet to get out of the dead zone. We re-established communication with the jet and cleared it for takeoff. Tech ops needs to find a solution so that the entirety of all runways are receiving radar coverage for all aircraft types. This problem should not persist as it could potentially lead to some very unsafe situations if; for instance; cancel takeoff clearance instructions are not heard.

Original NASA ASRS Text

Title: SFO Tower Controller reported a radio 'dead spot' identified at the approach end of Runway 1R that continually affects lower profile jets when in position on the runway.

Narrative: I was working Local Assist. Aircraft X was instructed to line up and wait on Runway 1R. When in position; the Local Controller attempted to reach Aircraft X on the frequency several times; but was unable. This has happened many times before with lower profile jets (smaller Citations; Lear Jets; Phenoms; etc). There is apparently a dead spot where the tower antennas do not reach low profile jets while they are in position on Runway 1R. The only way to reach them is to relay a message to them through another aircraft. I told the Local Controller about this and told them that they should tell an air carrier jet who was holding short of Runway 1R to instruct Aircraft X to move up a few feet to get out of the dead zone. We re-established communication with the jet and cleared it for takeoff. Tech Ops needs to find a solution so that the entirety of all runways are receiving radar coverage for all aircraft types. This problem should not persist as it could potentially lead to some very unsafe situations if; for instance; cancel takeoff clearance instructions are not heard.

Data retrieved from NASA's ASRS site 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.

Attributes
ACN	1501735
Time
Date	201712
Local Time Of Day	0601-1200
Place
Locale Reference	SFO.Tower
State Reference	CA
Environment
Light	Daylight
Aircraft 1
Make Model Name	Citationjet (C525/C526) - CJ I / II / III / IV
Operating Under FAR Part	Part 91
Flight Phase	Taxi
Route In Use	None
Flight Plan	IFR
Person 1
Function	Handoff / Assist
Qualification	Air Traffic Control Fully Certified
Events
Anomaly	ATC Issue All Types

Sfo tower controller reported a radio 'dead spot' identified at the approach end of runway 1R that continually affects lower profile jets when in position on the runway.