Aircraft Ice Detection Standard
Even a thin layer of ice on the wings of an aircraft can have disastrous consequences. With this is mind, ongoing research into aircraft ice detection has resulted in standards being set with regard to equipment used and preventative measures being taken. The new SAE (Society of Automotive Engineers) International aerospace standard focuses on detecting ice before the airplane takes off.
Known as AS5681, it specifies the minimum operational performance requirements for Remote On-Ground Ice Detection Systems (ROGIDS). ROGIDS have been in use since the early part of the 1990s, but until now there have been no specified requirements to measure with accuracy whether ROGIDS was superior, or even equivalent to, human visual or tactile competency. These issues are addressed by AS5681 which provides specifications for manufacturers to comply with and thereby obtain the necessary regulatory approvals. The development of these specifications was as a result of very thorough testing by a number of knowledgeable and experienced members in the industry. Adherence to the specifications would result in equipment that accurately detects ice far better than humans can, resulting in improvements in safety as well as avoiding delays caused by airplanes having to return to de-icing pads.
ROGIDS makes use of a specialized infrared camera in order to detect the unique patterns caused by refraction of infra-red light when it detects ice on critical aircraft surfaces. This has proven to be particularly valuable in detecting even very thin sheets of clear ice which can be caused by snow or sleet and is virtually impossible to see with the human eye.
Research included studies where ice samples were embedded beneath a residual layer of glycol-based de-icing fluid – something that occurs fairly frequently. The results of the studies revealed that personnel can easily detect even very thin ice tactilely when it is contained in a small area. However, visually detecting clear ice on bare and painted aluminum surfaces of an aircraft is much more difficult. It was shown that the ROGIDS prototype they were testing had abilities far superior to those of experienced de-icing personnel when it came to detecting ice patches of varying thicknesses and areas scattered on an aircraft wing.
These studies have shown that Remote On-Ground Ice Detection Systems have the potential to dramatically increase the level of ice detection when used for post de-icing inspections and consequently increase the safety of airplane travel in icing conditions.