A helicopter air ambulance descended and struck the ground in VMC with light fog. No damage to aircr...

Attributes
ACN	728043
Time
Date	200702
Local Time Of Day	1801 To 2400
Place
Locale Reference	airport : zzz.airport
State Reference	US
Altitude	agl single value : 300
Environment
Flight Conditions	Marginal
Weather Elements	Fog
Light	Night
Aircraft 1
Operator	common carrier : air taxi
Make Model Name	Helicopter
Operating Under FAR Part	Part 135
Flight Phase	climbout : takeoff
Flight Plan	None
Person 1
Affiliation	company : air taxi
Function	flight crew : single pilot
Qualification	pilot : multi engine pilot : commercial pilot : instrument
Experience	flight time last 90 days : 45 flight time total : 11300 flight time type : 120
ASRS Report	728043
Events
Anomaly	other spatial deviation
Independent Detector	other flight crewa
Resolutory Action	none taken : detected after the fact
Supplementary
Problem Areas	Weather Flight Crew Human Performance
Primary Problem	Flight Crew Human Performance

Narrative:

Upon departure from hospital at XA52 local time; I encountered some very thin scattered layers of forming fog at approximately 300 ft AGL. I could maintain visual contact with lights ahead of my helicopter and off to the right front several mi away. While maneuvering to remain clear of the forming fog layers; I inadvertently let the aircraft descend and contacted soft ground resulting in damage to the right side skid lights on the aft cross tube. At the time of the incident; I initially thought that I had had a bird strike since all I saw was a white flash and felt a thump and thought that I was still at 300 ft. The radar altimeter was set to alarm when descending below 200 ft. I do not recall hearing the warning sound from it. No other damage to the aircraft was noted upon postflt inspection. There was no pressure to take this flight from the hospital or my peers. The WX was above minimums for our operation and was forecast to remain so for the duration of the flight. The fog forming was not expected until after XC00 hours; but this fog began forming several hours earlier than expected. Rain showers and thunderstorms also formed that were not forecast; however; they were not a contributing factor to this incident.

Original NASA ASRS Text

Title: A HELICOPTER AIR AMBULANCE DESCENDED AND STRUCK THE GND IN VMC WITH LIGHT FOG. NO DAMAGE TO ACFT BUT THE PILOT DID NOT HEAR ALERTING RADIO ALTIMETER.

Narrative: UPON DEP FROM HOSPITAL AT XA52 LCL TIME; I ENCOUNTERED SOME VERY THIN SCATTERED LAYERS OF FORMING FOG AT APPROX 300 FT AGL. I COULD MAINTAIN VISUAL CONTACT WITH LIGHTS AHEAD OF MY HELI AND OFF TO THE R FRONT SEVERAL MI AWAY. WHILE MANEUVERING TO REMAIN CLR OF THE FORMING FOG LAYERS; I INADVERTENTLY LET THE ACFT DSND AND CONTACTED SOFT GND RESULTING IN DAMAGE TO THE R SIDE SKID LIGHTS ON THE AFT CROSS TUBE. AT THE TIME OF THE INCIDENT; I INITIALLY THOUGHT THAT I HAD HAD A BIRD STRIKE SINCE ALL I SAW WAS A WHITE FLASH AND FELT A THUMP AND THOUGHT THAT I WAS STILL AT 300 FT. THE RADAR ALTIMETER WAS SET TO ALARM WHEN DSNDING BELOW 200 FT. I DO NOT RECALL HEARING THE WARNING SOUND FROM IT. NO OTHER DAMAGE TO THE ACFT WAS NOTED UPON POSTFLT INSPECTION. THERE WAS NO PRESSURE TO TAKE THIS FLT FROM THE HOSPITAL OR MY PEERS. THE WX WAS ABOVE MINIMUMS FOR OUR OP AND WAS FORECAST TO REMAIN SO FOR THE DURATION OF THE FLT. THE FOG FORMING WAS NOT EXPECTED UNTIL AFTER XC00 HRS; BUT THIS FOG BEGAN FORMING SEVERAL HRS EARLIER THAN EXPECTED. RAIN SHOWERS AND TSTMS ALSO FORMED THAT WERE NOT FORECAST; HOWEVER; THEY WERE NOT A CONTRIBUTING FACTOR TO THIS INCIDENT.

Data retrieved from NASA's ASRS site as of January 2009 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.

A helicopter air ambulance descended and struck the ground in VMC with light fog. No damage to aircraft but the pilot did not hear alerting radio altimeter.