Volcano eruption
Erupted volcanic ash reaches high altitudes and easily is spread by winds. It can cause significant threat for aircraft over a large territory of the planet.
Volcanic pieces (rock particles) get into the engine, melt as there is temperature more than 1000 C, stick to the blades and compressor and result in engine flame out or cutting off or fooling of the engines temperature sensors. Volcanic ash is charged so it will negatively affect communication. Air speed indicators will be clogged and will fail to operate. Safety of the aircraft flying through volcanic ash cloud is endangered as volcanic parts floating in the air reduce visibility, can cause damage of the fuselage, lights and movable surfaces.
Communication problems
Radio communication is considered to be failed if during 5 minutes the crew or the ATC unit doesn’t answer the repeated calls through all available radio communication channels.
Communication problems
can be caused by a number of reasons
There are two types of communication failure- one-way communication failure and two-way communication failure.
One-way communication failure is a situation when either pilot or controller is unable to transmit or receive a message.
Two-way communication failure is a situation when both pilot and controller are unable to transmit and receive a message.
In the event of one-way communications (i.e. aircraft can receive only), the controller may request the aircraft to make identifying turns, flash its navigational lights, transmit codes or IDENT signals on the transponder, rock its wings, etc, to acknowledge clearances or instructions
When it is known that two-way communication failure has occurred, ATC shall maintain separation between the aircraft having the communication failure and the other aircraft based on the assumption that the aircraft will operate in accordance with VMC or IMC.
In the event of two-way radio communication failure the pilot-in-command shall 1) use all available facilities, take measures to re-establish communication with the ATC directly or by means of other aircraft. In such cases, if necessary, the emergency frequency 121.5 MHZ may be used.
2) Transmit position reports and intentions, assuming the aircraft transmitter is operating, and prefixing all transmissions with “TRANSMITTING BLIND”.
3) Turn on landing lights, beacons, and strobe lighting.
Adherence to the appropriate RCF emergency procedures depends on the flight conditions - VMC or IMC.
In VMC:
Pilots shall
set transponder to Code 7600
continue to fly in visual meteorological conditions
land at the nearest suitable aerodrome
report the arrival by the most expeditious means to the appropriate air traffic control unit .
In IMC
1)Crew has to set squawk 7600, maintain the last assigned speed and level, or minimum flight altitude if higher, for a period of 7 minutes following the aircraft’s failure, to report its position over a compulsory reporting point and thereafter adjust level and speed in accordance with the filed flight plan;
2) In the event of radio communication failure directly after take-off, the pilot-in-command shall carry out approach according to the established pattern and land at the departure aerodrome.
3) If it is impossible to land at the departure aerodrome after take-off (due to meteorological conditions or if the aircraft mass exceeds the landing mass and fuel jettison is impossible etc.), the pilot-in-command has the right:
a) to proceed to the destination aerodrome according to flight plan. Complete a normal instrument approach procedure as specified for the designated navigation aid or fix; and land, if possible, within 30 minutes after the estimated time of arrival
b) to proceed to the alternate aerodrome at the flight level assigned by the ATS unit or at proximate lower flight level (in accordance with vertical separation rules), but not below minimum safe flight level.
ATC will consider aircraft experiencing communication failure if the expected report is missing within 5 minutes.
Firstly it is necessary to call the aircraft on definite frequencies (on current and previous sector frequencies) and identify whether it is one-way communication failure or two-way communication failure.
If an identified aircraft experiences a radio failure the radar controller shall instruct the aircraft to make a turn(s) or set another transponder code. If movement of the plane or another code indicates that the aircraft receiver is operating the controller shall continue to pass instructions blind or try to resume normal radar service.
After attempts to establish normal two-way radio communication have failed, controllers are to carry out the following standard radio failure procedures:
Maintain separation between the radio failure aircraft and other known traffic;
When operating in RVSM airspace, provide a minimum vertical separation of 2000 feet between the radio failure aircraft and any other aircraft;
Give pertinent information about the movements of the radio failure aircraft to other aircraft in the presumed vicinity;
Ask aircraft in the presumed vicinity to establish communication with the radio failure aircraft and relay messages;
Use all means possible to monitor the aircraft’s progress;
Transmit, on the appropriate frequencies: level, route and EAT (or ETA) to which the radio failure aircraft is assumed to be adhering; the weather conditions at the destination aerodrome, a suitable alternate and, if practicable, in areas suitable for a descent through cloud.
When, in consultation with the operator, instructions to divert have been transmitted to the radio failure aircraft, inform the alternate aerodrome and request that they attempt to establish communication;
During flight without radio communication at night, the crew shall, if possible, indicate aircraft position by periodical switching on of onboard landing lights or by onboard lights flashing.
In order to avoid miscommunication both pilots and controllers have to
Pronounce each word clearly and distinctly
Maintain an even rate of speech (not exceeding — typically — 100 words per minute)
Make a slight pause preceding and following numerals; this makes them easier to understand
Maintain the speaking volume at a constant level
Be familiar with microphone-operating techniques (particularly in maintaining a constant distance from the microphone )
Usage of standard phraseology (nonstandard phraseology or the omission of key words may change completely the meaning of the intended message, resulting in potential conflicts)
The most significant example is the North American phrase “Taxi into position and hold.” It has the same meaning as the ICAO phrase “Line up and wait,” whereas the ICAO phrase “Taxi to holding position” is a clearance to taxi to and hold at a point clear of the runway. Always read back the necessary clearances:
√ ATC route clearances
√ Clearances and instructions to enter, land, take off, hold short of, cross or backtrack on RW
√ Runway in use
√ Altimeter setting
√ ATC transponder code
√ Altitude or flight level instructions
√ Heading and speed instructions
√ Transition levels
Miscommunication can cause RW incursion.
Runway incursion is called "Any occurrence at an aerodrome involving the incorrect presence of an aircraft, vehicle or person on the protected area of a surface designated for the landing and take off of aircraft".
We can speak about typical scenarios of RW incursion
Controller related situation: not having visual contact with the aircraft due to poor visibility controller instructs one plane to clear the RW but pilots misunderstand the instruction or appear on the RW by mistake and without checking their position ATC clears another aircraft for take off.
Pilot related situation: pilots in unfamiliar airport acknowledge taxing instructions but being disorientated by night time or hot spots enter the active RW.
Driver related situation: ground vehicle driver crosses the RW without ATC clearance.
There are also contributing factors: poor visibility, night time when there is no visual contact, complexity of airport marks and signs that can confuse the pilots, usage of non-standard phraseology that can result in misunderstanding.
CONTROLLER-PILOT DATA LINK COMMUNICATION
CPDLC is communication system which allows pilot and controller to communicate with the help of data link. CPDLC allows controllers to issue common clearance directions, such as flight level assignments and constraints, frequencies, route changes and deviations, speed restrictions, and requests for information. The flight crew can then respond.
The CPDLC application provides air-ground data communication for the ATC service. This includes a set of clearance/information/request message elements which correspond to voice phraseology employed by Air Traffic Control procedures. The controller is provided with the capability to issue
level assignments
crossing constraints
lateral deviations
route changes and clearances
speed assignments, radio frequency assignments
various requests for information.
The pilot is provided with the capability to respond to messages, to request clearances and information, to report information, and to declare an emergency. The pilot is, in addition, provided with the capability to request conditional clearances (downstream).A “free text” capability is also provided to exchange information not conforming to defined formats.
The benefits of flight deck integrated ATC systems include the following:
√Enhanced flight crew situational awareness.
√Shift of workload from controller to pilot. For example, controllers can issue sequence positions and pilots can be left to maintain their sequencing without further controller direction.
√Alleviates miscommunication problems.
√Improved efficiency and system capacity by allowing a reduction of necessity to repeat missed messages or correct errors in read-backs.
√Data-link communication can act as a back-up to traditional radio communication.
√Digital communications are (generally) more reliable than analogue communications.
But these radio communications are inherently vulnerable to error.
Resources for radio communications (particularly frequencies) are limited.
When there is congestion of air traffic it requires from controller high workload
Congestion on ATC frequencies results in communication errors, particularly due to blocked transmissions (which themselves only generate further congestion).