An aircraft operated as a controlled flight shall maintain continuous voice communication watch on the appropriate communication channel of, and establish two-way communication as necessary with, the appropriate air traffic control unit in or just before entering his controlled area.
Note that in IVAO, Text mode is possible if voice communication cannot be established due to technical problems only, or cannot be possible due to personal issues.
If a communication failure occurs, the aircraft shall attempt to establish communications with the appropriate air traffic control unit using all other available means.
In addition, the aircraft, when forming part of the aerodrome traffic at a controlled aerodrome, shall keep a watch for such instructions as may be issued by visual signals. (Note that in the IVAO network, the visual signals cannot be created and generated; this sentence is given for information only).
This paragraph is written for the IVAO Network resource as the communication mode is using software and not direct radio communication on air.
When you failed to establish communication with the air traffic controller, you can try these solutions by order:
Switch your radio to UNICOM or 122.800 and switch to the air traffic controller frequency using the IVAO Pilot interface
Try to communicate by text mode on the air traffic controller frequency (or if this does not work, you can use private chat)
Try to contact nearby air traffic control and if reached, this air traffic control shall transmit aircraft messages.
If the solutions given have no effect and, the pilot is not capable to communicate:
Switch to UNICOM or 122.800 and provide auto information messages and try to contact another pilot, if possible, in text mode on UNICOM in order to make a text transmission.
If in visual meteorological conditions (VMC), the aircraft shall:
If in instrument meteorological conditions (IMC) or when the pilot of an IFR flight considers it is inadvisable to complete the flight under VMC conditions, the aircraft shall perform the following procedure:
a) In airspace where radar is not used in the provision of air traffic control, maintain the last assigned speed and level, or minimum flight altitude if higher, for a period of 20 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 (unless otherwise prescribed on the basis of regional air navigation agreement).
This can be applicable in IVAO in oceanic regions or some area control centres over some areas outside radar coverage.
b) In airspace where radar is used in the provision of air traffic control, maintain the last assigned speed and level, or minimum flight altitude if higher, for a period of 7 minutes following:
whichever is later, and thereafter adjust level and speed in accordance with the filed flight plan;
c) When being radar vectored or having been directed by ATC to proceed offset using area navigation (RNAV) without a specified limit, rejoin the current flight plan route no later than the next significant point, taking into consideration the applicable minimum flight altitude;
d) Proceed according to the current flight plan route to the appropriate designated navigation aid or fix serving the destination
aerodrome and, when required to ensure compliance with e) below, hold over this aid or fix until commencement of descent;
e) commence descent from the navigation aid or fix specified in d) at, or as close as possible to, the expected approach time last received and acknowledged; or, if no expected approach time has been received and acknowledged, at, or as close as possible to, the estimated time of arrival resulting from the current flight plan;
f) complete a normal instrument approach procedure as specified for the designated navigation aid or fix; and
g) land, if possible, within 30 minutes after the estimated time of arrival specified in e) or the last acknowledged expected approach time, whichever is later.