An Air Methods EMS crew reverted to a Localizer approach at Bluefield, West Virginia once upon a time. The approach at that time was very unusual in that it did not have a locator outer marker (LOM) and relied upon radar vectoring.
The crew distinctly asked ATC for a vector that would take them well outside the glide slope interception point but for some reason still found themselves unable to obtain the glide slope indication following an early turn-in vector by ATC.
They probably assumed an instrument or system failure and proceeded with the Localizer approach.
The hit a mountain on the far side of the airport at approximately the MDA and killed all four aboard the Bell 412.
There were a host of other issues surrounding that crash that went unremarked about during the investigation thus one cannot put it down to a "simple" crew failure.
The point to be remembered.....if you do not know without doubt why you have no glide slope.....GO AROUND! Do so early...do so whenever any ambiguity occurs. No one got killed climbing away from the ground and returning for another approach. Damn the commercial department....it is your hide that will be plastered to the Smoke House Door if you encounter the Earth at a most in-opportune time.
The DME was not in the "Hold" position as it should have been if they had been using the on-field Vortac for DME mileage readouts and the Loran/GPS was not set to the airfield coordinates for assistance in Situational Awareness. The aircraft was the company spare which had been flown in by the Corporate Check Airman. The Crew had done a bag drag from their normal duty aircraft to the spare and departed on a flight they had turned down earlier in the day due to the inclement weather. With the Check Airman on site, they may have felt pressured to make the IFR flight despite having refused earlier.
The Captain of the aircraft was the Base Manager, Training Captain, and Safety Officer.