A radio altimeter is a necessity for alerting the pilot  when inadvertently going below the minimum altitude.  Barometric altimeters are subject to inaccuracies that  become important in helicopter IFR operations, especially  in cold temperatures.  airport/heliport landing, diverting to better conditions,  or initiating an emergency transition to IFR. Pilots should  be able to readily identify the minimum initial altitude  and course in order to avoid CFIT. Current IFR en route  and approach charts for the route of flight are essential.  A GPS navigation receiver with a moving map provides  exceptional situational awareness for terrain and obstacle  avoidance.  AC 150/5390-2, Heliport Design, provides recommendations  for heliport design to support non-precision, approach with  vertical guidance (APV), and precision approaches to a  heliport. When a heliport does not meet the criteria of AC  150/5390-2, FAA Order 8260.42, United States Standard  for Helicopter Area Navigation (RNAV), requires that an  instrument approach be published as a Special procedure  with annotations that special aircrew qualifications are  required to fly the procedure. Currently, there are no  operational civil IFR heliports in the U.S., although the U.S.  military has some non-precision and precision approach  procedures to IFR heliports.  Training for an emergency transition to IFR should  include full and partial panel instrument flight, unusual  attitude recovery, ATC communications, and instrument  approaches. If an ILS is available and the helicopter is  equipped, an ILS approach should be made. Otherwise, if  the helicopter is equipped with an IFR approach-capable  GPS receiver with a current database, a GPS approach  should be made. If neither, an ILS or GPS procedure is  available use another instrument approach.  Upon entering inadvertent IMC, priority must be given  to control of the helicopter. Keep it simple and take one  action at a time.  7-17  • Communicate. Attempt to contact ATC as soon as  the helicopter is stabilized in the climb and headed  away from danger. If the appropriate frequency is  not known, you should attempt to contact ATC on  either very high frequency (VHF) 121.5 or ultra high  frequency (UHF) 243.0. Initial information provided  to ATC should be your approximate location, that  inadvertent IMC has been encountered and an  emergency climb has been made, your altitude,  amount of flight time remaining (fuel state), and  number of persons on board. You should then  request a vector to either VFR weather conditions  or to the nearest suitable airport/heliport that  conditions will support a successful approach. If  unable to contact ATC and a transponder code  has not been previously established with ATC for  inadvertent IMC, change the transponder code to  7700.  • Climb. Climb straight ahead until your crosscheck is  established. Then make a turn only to avoid terrain  or objects. If an altitude has not been previously  established with ATC to climb to for inadvertent IMC,  then you should climb to an altitude that is at least  1,000 feet above the highest known object and that  allows for contacting ATC.  • Control. First use the wings on the attitude indicator  to level the helicopter. Maintain heading and  increase to climb power. Establish climb airspeed  at the best angle of climb but no slower than V$_{MINI}$.  IFR Heliports 