The nightmarish events of Sept. 11 have prompted sweeping changes in aviation security. After much debate, the U.S. Congress in November 2001 passed and the President signed legislation that mandates a new agency in the Transportation Department (DoT) to handle security and federalizes airport screeners. Congress authorized $500 million for work on cockpit doors, transponders, video systems and other technologies. The Federal Aviation Administration (FAA) expects airlines to present proposals for long-term door mods, as well as transponder and video system plans, by April 2002 and to complete work by April 2003. The agency plans to start spending the money in the next four months or sooner and has set up a special certification team to expedite assessments.
In November 2001, an FAA-industry transponder task force described three modification methods to assure continuous transmission in flight. In addition, ARINC Inc. advocates an ACARS (aircraft communications addressing and reporting system) -based approach and Qualcomm Inc. touts a satcom system that provides "backup transponders with aircraft identification, altitude, speed and location information."
The first method described by the task force is a transponder software modification. Manufacturers Honeywell and ACSS, an independent company owned by L-3 Communications and Thales, support this approach. ACSS plans to offer a software mod that could be performed in the field and cost less than $10,000. Honeywell intends to offer both a software solution and the "panic button" approach, according to Ben Mcleod, director of business development for airlines and avionics products.
The panic button approach, the second method, would add a remotely mounted unit that "mimics the control panel in the flight deck," Mcleod explains. If the flight deck control panel were damaged or disabled, the panic button would activate this box, ensuring continuous transponder transmission. The signal could only be reset from the ground. "When the panic button is pressed, the [cockpit] control panel is switched out and the hidden control panel is switched in," says Cyro Stone, a member of the government-industry task force and an ACSS senior technical staff member.
A third option involves hardware modifications to the existing control panel. This idea was supported in industry discussions by technical personnel at United Airlines but had not been endorsed by the carrier’s management at press time. This option would prevent the transponder from being set in the standby position while the aircraft is in flight, explains a United specialist. It would be simpler, less time-consuming and less expensive than the other concepts, he says. But it may be a hard sell to FAA, as it would limit transponder functionality and could be defeated more easily than the other two approaches, other avionics experts say.
ARINC has proposed a concept derived from a planned general aviation product called "security messenger." The device contains a built-in GPS unit and ACARS radio and processor units. It would cost in the $10,000 range, says Rolf Stefani, director of business development. Installed in an "inaccessible location" and independent from the avionics systems, the backup unit would transmit the latitude/longitude, heading, ground speed, altitude and identification of aircraft to the ground. The air transport version could be certified by February 2002. It also could serve ground applications if interfaced to other sensors, alerting owners of intrusion, smoke and fire on parked aircraft.
Enhanced Vision
As airline and corporate aviation procurements of flight deck head-up displays (HUDs) increase, look for growing interest and sales of add-on enhanced vision systems (EVS). The basic HUD projects key guidance information onto a transparent screen in front of pilots, allowing them to fly an accurate instrument approach while looking ahead through the windshield for the runway. But a major HUD drawback is that the pilot’s forward visibility in foggy or cloudy conditions is not increased.
The EVS overcomes this limitation by using a small, forward-looking infrared detector in the aircraft nose, which can "see" the runway through intervening weather and present a moving, almost photographic image of the airport ahead, superimposed on the HUD guidance data. Future EVS developments will include a forward-looking millimeter-wave radar sensor to augment the infrared unit in torrential rain and certain unusual fog conditions.
In October 2001 Gulfstream Aerospace, Savannah, Ga., obtained FAA approval to install Kollsman’s EVS in its Gulfstream V corporate jet. Separately, CMC Electronics, Ottawa and Cincinnati, and MaxViz, Portland, Ore., are each developing EVS equipment and both forecast FAA approval in late 2002.
CPDLC
CPDLC (Controller Pilot Data Link Communications) is forecast to increase airspace capacity and reduce delays by using digital data messages to replace conventional voice communications except during landing and departure phases and in emergencies. Today the average pilot/controller voice exchange takes around 20 seconds, compared to one or two seconds with CPDLC. In FAA and Eurocontrol simulations, air traffic controllers indicated that CPDLC could increase their productivity by 40 percent without increasing workload. Airline cost/benefit studies indicate average annual savings of around $12 million and $28 million, respectively, in the terminal and en-route phases, due to CPDLC-related delay reductions.
Extensive Eurocontrol airline tests have proved the system’s feasibility: an American Airlines Boeing 767-300 in mid-2001 operated the first scheduled commercial flight under total CPDLC control from Maastricht, Netherlands, to the Paris Charles de Gaulle airport.
An initial FAA CPDLC ground station at the Miami air route traffic control center (ARTCC) is slated to conduct further tests with four American Airlines’ CPDLC-equipped Boeing 767s, using ARINC’s aeronautical telecommunication network (ATN)-compliant VHF digital link (VDL) Mode 2 (VDL-2) this year. Plans, however, may change in light of current financial conditions. A second phase will establish a nationwide CPDLC ground station network, while the third phase will transition from VDL-2 to the future voice/data Next generation air/ground Communications (Nexcom) system.
Digital Voice
Nexcom, the FAA’s ambitious effort to introduce digital voice into the National Airspace System (NAS) and ease congestion in the VHF air-to-ground frequency band, moved out with a 10-year, $580-million contract to ITT Industries last year for as many as 37,650 ground-based multimode digital radios (MDRs). Nexcom is firmly committed to VDL-3, with both digital voice and data link capabilities. But, in response to user concerns, the program also has begun work on a backup plan to implement 8.33-KHz analog voice, as is being done in Europe.
Initially the MDRs provided by ITT and partner Park Air Systems will use analog voice at 25-KHz channel spacing. But the radios are capable of operating at the 8.33-KHz spacing mandated by Eurocontrol and will work with VDL-3 systems.
MDR factory acceptance tests are slated for March 2002, followed by a three-month-long FAA operational test and evaluation phase. ITT expects a deployment decision by October 2002, deliveries beginning later in 2002, and fielding commencing in the first quarter of 2003. The first MDR deployments will be to en-route control sectors. FAA also expects before October 2002 to award multiple engineering development contracts covering radio interface units and ground network interface units.
The Nexcom program plans a proof-of-concept demonstration of VDL-3 prototype avionics (built in-house or by Mitre Corp.) and ground systems for late 2002, says Jim Eck, FAA’s air/ground communications product team lead. This will demonstrate elements such as voice encoding, voice control, controller override, stuck mic resolution, anti-blocking and urgent downlink request, plus the ability to pass rudimentary data back and forth over the same channel at the same time, he says.
RTCA has developed an integrated minimal operational performance standards (MOPS) document for VDL-3 transceivers and communication management units, Eck says. The next step is a "draft recommended characteristics" document, which the Airlines Electronic Engineering Committee (AEEC) is to provide by October 2002. This document will take existing ARINC 750 radio specs and add in the VDL-3 components based on the integrated MOPS. A VDL-3 rule making is expected in 2005.
Nevertheless, the idea of analog voice has not been dismissed. Last October an industry-government panel, initiated by the FAA administrator, recommended pursuing both analog and digital paths. The Nexcom Aviation Rulemaking Committee (NARC) said FAA should continue to support VDL-2 and expedite the demonstration and validation of VDL-3, but also develop a plan to implement an 8.33-KHz analog voice system, says NARC chairman John Kern. He says that if the air traffic communications system moved to 8.33-KHz spacing when (and if) the current system is saturated at the end of the decade, there will be "another 20 years’ supply of frequencies."
"Two things have to happen for [VDL-3]," says Steve Zaidman, associate administrator for research and acquisition. "The frequency availability and length [of time] for 8.33-KHz [channel depletion] won’t be 20 years, but much shorter," and there must be a business case for data link under VDL-3. Moreover, "both … have [to happen] in the next two years … to go to a rule making and have it come out VDL Mode 3."
Aviation Satcom
Uncertainties in the aviation market and in the larger economy may dampen satellite communication’s traditional 10 percent growth rate in 2002. But new high-speed data services for the cabin, such as Inmarsat’s 64-kilobit/sec (Kbit/sec) Swift64, will attract customers. Security applications likewise will probably provide a boost. And airlines will continue–although at a slower rate–to equip with future air navigation system (FANS) avionics, of which satcom is a basic component.
Honeywell is promoting satcom or airphones for transmitting cockpit audio to the ground. The company prefers these methods to VHF or HF radio because they are "more private and more appropriate" communications links.
The revived satellite communications company, Iridium, has proposed the idea of using its constellation for real-time cockpit voice and flight data monitoring. And Qualcomm Inc. has advanced an aviation solution based on the Globalstar constellation.
The next big phase in air transport satcom could be high-speed data, such as Inmarsat’s Swift64. EMS Technologies already has announced the availability of a dual-channel, 128-Kbit/sec, Aeronautical Data Terminal (ADT-1000), for e-mail, Internet and voice and fax services. Honeywell/Thales, RockwellCollins, Ball Aerospace and Thrane & Thrane also plan to build Swift64 hardware.
Honeywell last year announced the certification of the MCS-7000 and MCS-4000 satcom systems developed with Thales for the corporate and air transport markets. Both systems will have Swift64 options and both are compatible with ATN.
Collins plans to debut Swift64 hardware for air transport and general aviation this fall. The Collins High-Speed Transceiver, HST-900, will work with the company’s existing SAT-906 satcom system. Initially, the HST-900 will enable cabin e-mail and Internet access, but it also will support eFlight applications, as these become available. The HST-900 provides one 64-Kbit/sec data channel; the SAT-906 provides one data channel and up to five voice channels at 9600 bits/sec.
MLS
Once felt to have been superseded by GPS as the future precision landing guidance system, microwave landing systems (MLS) are making a comeback. In 2001, Rockwell Collins flew more than 100 Category IIIb (very low visibility) MLS approaches with its multimode receiver (MMR) at U.S. and European airports.
Collins expects technical standard order (TSO) approval early in 2002. Its first customer is the U.S. Air Force, which operates a number of MLS ground stations, both in the U.S. and overseas. Follow-on sales could be to European airlines, such as British Airways, which has specified MLS-equipped MMRs for the 87 Airbus 320 variants it has on order. Honeywell and Thales also are developing MMRs.
Category III MLS ground stations serve runways at Amsterdam, Frankfurt and Paris Charles de Gaulle airports. In mid-2001, France ordered MLS installations for all its Category III airports, and the UK is shortly expected to announce a contract for up to 27 Category III installations. Four systems are planned for London Heathrow, plus two each at Gatwick, Stansted and Manchester, and single installations elsewhere in the country.
Loran-C
The obvious need for a GPS backup system–underscored by the GPS vulnerability study published by the DoT last year–has revived the prospects for Loran-C. Advocates point to the system’s all-altitude, non-line of sight coverage, coupled with the development of p-static-resistant, H-field antennas and digital, all-in-view receivers which can acquire, process and track all Loran transmitters within reception range. Typically, that adds up to more than 30 separate stations, compared with the four or five station "chains" used now. The new, single-module receivers will fit inside and be integrated with airborne GPS units.
Loran-C proponents also emphasize the system’s greatly improved position accuracy and, even more important, its precise timing capability. Future avionics systems, such as the VHF Nexcom voice/data radios and Free Flight’s automatic dependent surveillance-broadcast (ADS-B) will rely on GPS timing for operation, as do many of the nation’s critical government, commercial and industrial activities, making a GPS timing backup essential. FAA flight tests demonstrated that Loran-C stations also can transmit the GPS integrity and accuracy corrections normally provided by WAAS.
The U.S. Coast Guard–the official Loran-C custodian–in late 2001 awarded contracts valued at over $40 million to upgrade the nationwide Loran network.