Interference with compasses/slaved gyros at hospital helipads
 

The FAA has issued a Safety Alert alerting helicopter operators to a special hazard when operating in the vicinity of hospital helipads.
The SAFO has been issued following reports by pilots and operators of EMS helicopters who experienced interference emanating from active operating MRI scanner equipment, which degraded the indicated directional accuracy of standby compasses and slaved gyroscopic systems.
The pilots reported large deviations in accuracy of their slaved gyroscopic systems while departing from helipads, until flying out of the interfering magnetic field of the MRI.
In summary:

• EMS, law enforcement and military pilots departing from hospital helipads, are advised to verify the accuracy of their magnetic direction indications by comparing their magnetic directional instruments against a known heading for departure.
• Instruments should be re-verified before proceeding “on course.”
• Pilots should be prepared to select the “free” directional gyro function, if available, and “slew” the compass heading to a correctly known magnetic heading.
• Alternatively, pilots may choose to ignore observed erroneous directional indications until clearing the vicinity of the interfering magnetic field of the MRI scanner equipment.

Link to full SAFO

Now I know why whenever we are aiming for Lincoln hospital we always end up in the ASDA carpark!

A good number of helipads in the Sydney area have a shorter warning to that effect posted already - although the writing is a bit small until you actually arrive on it..... so probably won't help your ASDA diversion?

New MRI scanners produce up to 3 tesla which is a pretty strong field.

Definition here - http://en.wikipedia.org/wiki/Tesla_(unit)

Bertie,

Both you and I know that you end up at ASDA because the paramedics are more interested in two-for-one offers on pies, biscuits and cakes !! :)

.....I thought it was for the cheap deals in womens underwear!

On a serious note; in a similar vein (!) to the MRI field problem, where do all the wiggyamps go when we defibrillate in flight?

Hopefully into the patient, and certainly not into the pilot. Unless......

I guess the leakage is stored in the airframe until it grounds or goes out through the static wick dischargers.