interesting to learn:
In a similar case as UPS B744 in DXB, when the pilot could not see or change freq. the R VHF is always set to 121.5, easy to use, so if a pilot uses only 121.5 all the way from cruise FL to PAX evac in any airport, would he be able to communicate with all ATC concerned?
Any ATC station can communicate in 121.5?
Are the FIRE CREWS also on 121.5?
A change of frequency in not always possible as the UPS case showed