Most helicopter EMS programs operate under VFR only. With the high number of weather-related accidents lately, the question of mandating IFR operations is talked about a lot. I do not know of a study that compares weather-related accidents for VFR-only versus IFR helicopter EMS programs. My guess would be that IFR programs would have a lower rate of these kinds of accidents.
I have flown for two IFR programs, Mayo One (BK117 C1) and CareFlite Dallas (Augusta 109E). In both programs the pilots in general were more comfortable flying in lower weather. This is for several reasons, but mainly the extra training and the fact that they were flying a fully IFR-certified helicopter. Also, I think being IFR trained and experienced helps pilots make better go/no-go weather decisions.
Filing an IFR flight plan does take a few extra minutes. However, using the IFR system to respond to a trauma call (flight on a highway for example) is rarely done. In these cases the ground crew would have to transport the patient to the closest instrument approach (normally an airport). If we couldn’t save any time, we would advise the dispatcher that transport by ground would be faster. Time is critical and a responsible pilot must make sure not to risk delaying patient care. I seldom launched on a flight under IFR.
However, there were several times when after departing VFR and on the return flight to the hospital weather deteriorated. I would call approach and receive an IFR clearance and vectors to the hospital’s GPS approach. In general, I’d say that getting a pop up clearance was not a problem and caused minimal if any delay. Keep in mind this was Rochester, Minnesota; ATC was not as busy as some larger airports and very accommodating to Mayo One. In Dallas/Fort Worth (CareFlite) ATC was much busier but also very helpful. Here pilots are sometimes asked to turn to a different heading and may be asked to maintain VFR for a short period. Normally they will get you in the IFR system and to an instrument approach with minimal delay.
The IFR system is definitely more fixed-wing friendly. Compared to airplanes, helicopters operating under IFR is still relatively new. The development of low-level GPS routing and WAAS approaches will help change that in the future.
In general, I do not think EMS programs are able to justify the added cost of an IFR program by the increased number of flights (therefore revenue) that IFR capability brings. I think the more important point is the increased pilot proficiency it provides and the extra options it gives the pilot. In an industry that is always trying to cut costs I think highly of the programs that understand the benefits and increased safety that an IFR program brings. If I were to return to EMS flying I would definitely want to fly for an IFR program.