Chapter 19
Incidents on the Frequency
Handle stuck microphones on guard, broadcast laser warnings on final, and coordinate police and ground vehicles for unruly passengers in the tower.
Three events on the tower frequency
The earlier situation chapters dealt with events that reshaped the airport operation for everyone on the field. In chapter 15, a shifting wind put a tailwind or crosswind component past the limit and forced a runway change, and in chapter 18, falling snow put ploughs on the pavement.
Many unusual days in the tower cab are smaller in scale and leave the active runway open. Nobody declares an emergency and traffic keeps moving, yet a problem breaks out on the radio that belongs to the local controller until it is resolved. Three of the most common are a stuck microphone that blocks the tower frequency, an unauthorised laser pointed at an arrival on final, and an unruly passenger restrained in the cabin of an inbound airliner whose crew asks for police to meet the flight.
Each of these three events has its own phraseology and procedures, and all three follow the same practical order in the cab: listen to what the frequency is telling you, handle the immediate control task for the aircraft involved, and then broadcast the warning or coordinate the surface movement so the rest of the airport stays safe.
A stuck microphone and the guard call
VHF aviation radios operate on a shared amplitude-modulated channel where one transmitter can use the frequency at a time. When a pilot's push-to-talk switch sticks closed or a kneeboard rests against a hand microphone button in the cockpit, that aircraft's radio puts a continuous carrier on the tower frequency.
In the tower cab, an open or hot microphone cuts you off from your traffic at once. While that carrier stays keyed, every other transmission on the frequency is blocked or buried in a heterodyne squeal whenever a second radio keys up. You cannot hear an arrival checking in on final or a departure reading back a clearance, and no pilot on the frequency can hear anything you transmit. Often the crew with the stuck switch does not know their microphone is open, because their cockpit intercom sounds normal to them while everyone else on the tower channel hears cockpit background noise or a steady tone.
Keying your own transmitter repeatedly on the local frequency does nothing while the carrier is up. To reach the aircraft blocking the channel, you call on the VHF emergency frequency, known as guard, on one two one point five. Airliners monitor one two one point five continuously on a second radio while working ATC on their main radio, so a broadcast on guard reaches a crew whose main transmitter is keyed. You select guard, name the affected frequency, and ask aircraft to check their switches: "Attention all aircraft, stuck microphone on tower frequency, check your microphones." Crews check their switches and the carrier ends a few seconds later.
Recovering the frequency after the carrier drops
While the frequency was blocked, every aircraft on and around the airport kept moving at its normal speed.
Once the carrier drops and the pilot apologises, your rule is to trust only what was confirmed before the block began. A controller never assumes an instruction got through while the frequency was blocked. Whatever was said during the carrier was not heard and has to be said again, and any ReadbackThe pilot repeating a clearance or instruction back so the controller can verify it was received correctly.Open in the glossary that should have come during that window have to be asked for and verified on the clear channel.
You rebuild the picture in order of separation priority. An arrival on short final that still needs a landing clearance comes first, followed by a departure that lifted off before the block and still needs its handoff to Bayview Departure on one two four point six. Next, you return to the departure queue at the hold-short line. Giving a departure a heading instruction before its takeoff clearance is a normal way to keep traffic apart while the frequency recovers. In the form this manual and the simulator use, you state the heading, the runway, and then the takeoff clearance: "fly runway heading, runway two five right, Cleared for takeoffRunway two five right, wind two five zero at eight, cleared for takeoff.The runway is yours to fly from. Runway number first, then the wind, then the clearance, always in that order.Open in the glossary." Keeping the departure straight ahead on runway heading holds it clear of the arrival stream until departure takes the handoff.
Attention all aircraft, stuck microphone on tower frequency, check your microphones.
Bayview Tower, Southwest Three One Eight, sorry about that, we had a stuck mic.
Southwest Three One Eight, contact Bayview Departure on one two four point six.
One two four point six, Southwest Three One Eight.
United One One Nine Zero, fly runway heading, runway two five right, cleared for takeoff.
Fly runway heading, runway two five right, cleared for takeoff, United One One Nine Zero.
Laser illumination on the final
A second frequency incident happens on the final approach course, most often at night or in twilight. An arrival flying a straight-in final follows a predictable path over the city, where someone on the ground occasionally points a handheld laser at the aircraft. Green lasers are more common than blue. When a beam strikes a cockpit windshield, the glass scatters the light into a bright glare across the flight deck, and a direct hit can cause flash blindness in a pilot's eyes. A crew whose pilot has been hit may transfer control so the other pilot flies the remainder of the approach.
When a laser strike happens, the crew reports the colour, the side from which the beam came, their miles on the final, and their altitude, and they may add that one pilot has flash blindness and the other pilot is flying. You acknowledge the report straight away with "RogerRoger.I received your whole transmission. It does not mean yes, and it is not a readback.Open in the glossary, laser", pass what is useful such as the wind and landing clearance or any request the crew has, and do not question the crew while they finish the approach.
When a laser event is reported to an air traffic facility, broadcast on all appropriate frequencies a general caution warning every five minutes for 20 minutes following the last report.
PhraseologyUNAUTHORIZED LASER ILLUMINATION EVENT, (location), (altitude).
Terminal facilities must include reported unauthorized laser illumination events on the ATIS broadcast for one hour following the last report. Include the time, location, altitude, color, and direction of the laser as reported by the pilot.
noteAll personnel can expect aircrews to regard lasers as an inflight emergency and may take evasive action to avoid laser illumination. Additionally, other aircraft may request clearance to avoid the area.
Bayview Tower, Delta One Four Zero Seven, laser illumination, green laser from the left, four mile final runway two five right, two thousand feet, first officer has flash blindness, captain is flying.
Delta One Four Zero Seven, roger, laser, wind two four zero at eight, runway two five right, cleared to land.
Runway two five right, cleared to land, Delta One Four Zero Seven.
Attention all aircraft, unauthorized laser illumination event, four mile final runway two five right, two thousand feet.
Once you have handled the crew that reported the strike, you owe a warning to everyone else on the frequency. Under FAA Order JO 7110.65 paragraph 10-2-14, you broadcast a general caution on all appropriate frequencies using the reported location and altitude, repeat that caution every five minutes for twenty minutes following the last report, and place the event on the ATIS for one hour with the time, location, altitude, colour, and direction as reported. The laser report does not close the runway, though you watch the struck aircraft closely because aircrews may regard a laser as an in-flight emergency and take evasive action or Go aroundGo around, I say again, go around.An instruction or pilot decision to abandon the approach and climb straight ahead or on the missed approach, after which the aircraft is re-sequenced.Open in the glossary. For the aircraft following behind on final, the broadcast lets crews turn up cockpit lighting, stay focused on instruments through the reported altitude, or ask to avoid the area.
A restrained passenger and the police vehicle
The third incident is a cabin security matter on an inbound passenger flight. When a passenger becomes disruptive and the cabin crew restrains the person on board, the pilots call on final to ask for law enforcement to meet the aircraft. Nothing about a restrained passenger changes runway separation or the landing sequence; the aircraft still lands and clears the runway like any other arrival. What the crew needs from the tower before touchdown is confirmation that officers are on the way, so you acknowledge the report and tell the crew "police will meet the aircraft" along with their landing clearance.
Along with alerting law enforcement, the tower arranges where the aircraft will park, which is commonly a remote stand away from the terminal gates so police can board and remove the passenger out of the terminal flow. That arrangement brings a police vehicle onto the airport surface to meet the flight at the stand. Under the movement-area rules from chapter 14, any vehicle on the movement area, including a police car, crosses or enters a runway only on the tower's authorisation. The police unit calls the tower when approaching a runway, holds short of the hold line, and waits. When the runway is clear, you authorise the crossing by callsign and runway: "Police One, cross runway three three." When a departure is rolling or an arrival is on short final, you instruct the vehicle to wait: "Police One, Hold shortStop before the runway's holding position marking and do not enter. Hold short instructions must be read back.Open in the glossary of runway three three."
Bayview Tower, Alaska Two Seven, six mile final runway two five right, we have an unruly passenger on board, the crew has him restrained, request police meet the aircraft.
Alaska Two Seven, Bayview Tower, police will meet the aircraft, wind two five zero at seven, runway two five right, cleared to land.
Police will meet the aircraft, runway two five right, cleared to land, Alaska Two Seven.
Bayview Tower, Police One, holding short of runway three three on alpha.
Police One, cross runway three three.
Cross runway three three, Police One.
In the Sim
In ATC Simulator, these three incidents occur on tower shifts only and never in the approach seat. They are drawn from the Unusual occurrences setting of the shift, and the game never places one on top of an emergency or another incident. A departure's incident is always a stuck microphone after takeoff, while an arrival checking in on the final can bring any of the three; the laser and the police are arrival stories.
When a stuck microphone occurs, the crew keys the transmitter and cannot unkey it. While it is keyed, everything you say is blocked: nobody heard it and nothing executes. If nothing is done, it clears on its own between about fifty and a hundred seconds, the crew says "sorry about that, we had a stuck mic", and nothing in that time is charged to the controller. Broadcasting on guard with "attention all aircraft, stuck microphone on tower frequency, check your microphones" gets through whatever is on the frequency, the crew finds the switch about four seconds later, and you earn fifteen points on the score sheet. If nobody has a stuck microphone, the game says so and scores nothing.
In a laser incident, the crew reports the colour (with a green laser more usual than blue), side, miles on the final, and altitude, sometimes adding flash blindness in one pilot with the captain flying. You acknowledge with "roger, laser" inside thirty seconds for ten points and broadcast "attention all aircraft, unauthorized laser illumination event, (location), (altitude)" for twenty points. If the caution is not broadcast within two minutes, the game charges minus ten points for "laser not broadcast". Saying "roger, laser" to an aircraft that reported none is refused, and a laser caution cannot be broadcast while a stuck microphone holds the frequency.
Only an airliner with passengers can have an unruly passenger, never a freighter, a light single, or a fighter. The crew calls on final to report a restrained passenger and ask that police meet the aircraft, and saying "police will meet the aircraft" before touchdown scores fifteen points; if the tower never calls them, the airline calls the police at touchdown for no credit. The game picks a remote stand, and Police One drives out from the station, meets the aircraft for about two and a half minutes, and returns, calling the tower to cross runways along the way and obeying "police one, cross runway three three" or holding short when told to.
Training 23, "Incidents on the frequency", runs all three at Bayview Tower on runway two five right, with the stuck microphone first, then a departure given "fly runway heading, runway two five right, cleared for takeoff", then the laser, and then the police. Where an airport tower works the telephones for the police, the airline, and airport operations, and puts a laser report on the ATIS for an hour while repeating the caution every five minutes for twenty minutes, the game keeps the action on the frequency: the radio call alone summons the police, and a single broadcast ends the laser incident.
That is the last chapter of the handbook.