Date: 202107
Local time of day: 1201-1800
Location: EWR.Airport, NJ
Flight conditions: VMC
Aircraft: Commercial Fixed Wing
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Takeoff / Launch
ATC / advisory: Tower EWR
Aircraft component: Air/Ground Communication
Component problem: Malfunctioning
Reporter organization: Air Carrier
Reporter function: Captain; Pilot Not Flying
Reporter qualification: Flight Crew Multiengine; Flight Crew Instrument; Flight Crew Air Transport Pilot (ATP)
Human factors: Communication Breakdown; Confusion; Troubleshooting
Second reporter function: First Officer; Pilot Flying
Anomaly: ATC Issue All Types; Aircraft Equipment Problem Less Severe; Conflict Ground Conflict; Less Severe; Deviation / Discrepancy - Procedural Published Material / Policy; Ground Event / Encounter Ground Equipment Issue
Detector: Person Air Traffic Control; Person Flight Crew
When detected: Other takeoff
Result: Air Traffic Control Issued Advisory / Alert; Air Traffic Control Issued New Clearance; Flight Crew Requested ATC Assistance / Clarification
Contributing factors: Aircraft; Environment - Non Weather Related; Airport
Primary problem: Ambiguous

Narrative: Aircraft X joined taxi line for runway 4L. During the 45 minute taxi the flight was operating on upper antenna and all radio communications broadcast and received were normal. Flight was cleared to line up and wait 4L; comms normal. While in position a garbled; indistinct transmission was heard. Flight was expecting a takeoff clearance and called tower to verify they were broadcasting to us. No reply. Tower then came on and cleared flight to vacate runway; comm was loud and clear. Tower received our reply as well. Tower was then heard giving directions to a go around aircraft. The initial go around call to that flight was not heard by either pilot of our flight. Flight taxied back to departure end. Flight was cleared to line up and wait again; comms normal. Takeoff clearance was received and acknowledged. During initial takeoff roll tower came on frequency asking us if we were taking off. We replied we were and had acknowledged our takeoff clearance. Airborne tower wanted us to have our radio checked. Subsequent radio checks and communications with ATC were loud and clear for remainder of flight. I believe the transmissions during first takeoff clearance were blocked by a radio shadow.


Second narrative: While in position for takeoff on 4L at EWR both the Captain and I did not here the takeoff clearance given by tower which resulted in a go-around for another aircraft on final.  We did hear a garbled 'takeoff;' but that was it.  We both questioned it and when the Captain tried to clarify with tower were told to hold position and then received clearance to taxi off the runway; via BB and P.   Neither the Captain or I heard the takeoff clearance or the tower directed go around of the landing aircraft; but obviously the other aircraft did.  We than taxied back into position and it took the tower at least two tries to get us the takeoff clearance.  We only heard it once.  Upon departure we verified the VHF one was working correctly with multiple ATC agencies.   Sterile cockpit  procedures were followed and there were no conversations while in position on the runway.  Neither the Captain or I heard the original T/O clearance or the wave off call to the landing aircraft. The 10-7B pages for EWR state; 'Radio shadows exist in the vicinity of the first 1800 feet of the runways.' This is true and is an obviously known issue.    Not sure what causes this; whether it is certain airplanes or position of other planes on the taxiways.  At the time of the incident there was a line of 20+ airplanes on taxiway B. This condition is unsafe and needs to be corrected.


Synopsis: Air Carrier Pilots reported a communication dead spot at EWR airport.