Mar 17, 2005Passive UHF tags are safe for deployment on aircraft, according to U.S. aircraft manufacturer Boeing, which recently completed tests of passive RFID tags on a cargo plane operated by FedEx.
"We have shown we can use UHF passive tags on an airplane, and they work. The concept is sound," says Kenneth Porad, principal engineer for reliability and maintainability at Boeing. Boeing has already submitted results of its tests to the Federal Aviation Administration (FAA), which is expected to rule on the use of passive HF and UHF RFID tags on commercial aircraft later this year.
The FedEx trial, which begun on Oct. 6 and ran for 90 days, replicated a trial by Boeing and FedEx on the same MD10 freight airliner involving 13.56 MHz passive tags (see UHF Tags to be Tested on Planes). Smart labels used in the passive UHF test were placed at the same locations, including the flight deck, avionics compartment, cargo compartment and wheel wells, on the same aircraft used in the previous trial to ensure that no new variables were brought into the test.
The trial used 915 MHz Metal Mount Puck tags from Intermec Technologies. The 1- by 2-inch tags, which are not commercially available, were mounted on 2- by 3-inch labels, making them the same size as the previously trialed HF labels, which also carried printed bar codes.
The UHF tags had 1 kilobit of read-write memory that held the part number and serial number. In real deployment, however, those tags might carry the date the part was installed on the plane, a code identifying the stations where maintenance work took place, identification numbers of each mechanic who worked on the plane, and the dates and types of maintenance inspections performed on the plane. The write capability was not used during the trial; instead the tags were just read using the Intermec 1555 handheld reader.
One primary objective of the trial was to test how electromagnetic interference resulting from deployment of passive UHF RFID smart label in an airplane would affect the integrity of the smart label's data. During the test, FedEx used the freight airliners to transport cargo.
The chief advantage of UHF tags over HF, says Porad, is the increased read range of UHF tags. During the trial, the UHF tags were read from up to 15 feet away. With longer read ranges, a number of tags could be read at the same time tags and could be differentiated and pinpointed by software in the handheld readers, says Porad.
Boeing has long said that it expects to deploy both HF and UHF passive RFID tags, depending on the part being tagged and its location. An HF tag can operate in the same single frequency around the world, which gives it an advantage over a UHF tag because different nations of the world have assigned a different UHF frequency in which a UHF tag can operate. But if UHF tags were available that could be read across a range of frequencies, much of the incentive for HF tags would be lost because a single UHF tag could then be read anywhere in the world. Boeing believes such tags will be available this year.
"A tag could be read anywhere if it operated from 860 to 950 MHz. In Germany it could be read at 868 MHz, in Seattle at 915 MHz and in Japan at 950 MHz," says Porad.
Boeing says it next plans to test passive UHF RFID tags placed on jet engines to see if RFID tags can be used to tag and track engine parts, although no date has been set for the start of the trial. Plans were first announced last year, but the trial has yet to begin.
Boeing has been working together with Europe's Airbus Industries to promote the adoption of industry standard solutions for RFID on commercial airplane parts (see Boeing, Airbus Team on Standards). The two companies will hold their annual industry forum in Miami on Mar. 29-30.
