Fail-Op KSAT

 

Presented to the Performance-based Aviation Rulemaking Committee - Connectivity Working Group meeting #55 (PARC-CWG55). Thanks to Trey Turner (Southwest Airlines) and Kevin Kelley (FAA) for leading the three-day session. Also to L2 Aviation, especially Mark Lebovitz and Jim Nuse, for sponsoring the meeting at the Cincinnati/Northern Kentucky International Airport.

Video Link: https://youtu.be/66JK1Rudx9c

Key Outcomes

Peter Lemme presented a long-term vision (5+ years) for using dual independent KU/KA-band (KSAT) satellite systems as an equivalent to a single L-band system for aviation safety communications. The proposal aims to enable 1 L-band + 2 KSAT systems as a viable architecture, requiring regulatory acceptance that two design assurance level E systems can meet level D loss-of-function requirements

Market Disruption Waves

• Wave 1 (Current): Starlink dominance in aviation broadband; airlines committing full fleets to single provider
• Wave 2 (Near-term): Amazon Kuiper and other LEO constellations creating competitive marketplace; airlines delaying decisions to wait for options
• Wave 3 (5+ years): Airlines installing diverse, dual KSAT systems (e.g., Starlink + Amazon, or OneWeb + Telesat) for operational resilience
• GEO satellites undergoing renaissance with lower-cost, high-capacity solutions using larger launchers like Starship

Technology Evolution

Non-Terrestrial Networks (NTN)

• 3GPP standards convergence enabling common modems across satellite networks, similar to cellular GSM evolution
• Direct-to-device initiatives (Apple/Starlink) expanding to aviation; NTN modems in Ku/Ka frequencies replacing proprietary modems
• Seamless Air Alliance working with 3GPP for aeronautical NTN backhaul

Antenna & Modem Integration

• Multi-orbit antennas operational (600+ installations) supporting GEO and LEO from single beam
• Dual-beam solutions emerging: ThinKom+Hughes combo, Panasonic bolt-on for OneWeb, ViaSat electronically steerable array
• Starlink installing 3 separate antennas per aircraft; industry moving toward side-by-side installations in single location
• Modem-in-antenna architecture creating compact solutions; requires expanded function modem manager or connected application server for routing

Proposed Architecture

Dual Independent KSAT Requirements

• Two fully independent KSAT systems with separate antennas, modems, networks, and servers
• Diversity requirement: Different satellite networks to avoid common-mode failures
• Each system delivering gigabit-per-second bandwidth versus L-band's under 1 Mbps
• All radios operational simultaneously, providing continuous service value to airlines

Traffic Management

• Connected Application Server distributes data across three Ethernet domains: passenger connectivity, in-flight entertainment, aircraft information services
• Routing between dual channels requires either upstream arbitration or onboard router with elevated design assurance
• LEO for low-latency transactions; GEO for high-bandwidth streaming (70% of traffic)

Regulatory Barriers

Critical Issues Requiring Resolution

1. Design Assurance Level: ARP4754 does not permit two DAL E systems to credit as DAL D

   • Current rule: Two level D equals level C, but not two DAL E equals DAL D
   • Need regulator exception in consideration of this configuration

2. Spectrum Usage: Concern about using non-safety MSS spectrum (AMSS) for safety services

   • Route services provide interference priority; off-route does not
   • Performance-based approach suggested: demonstrate capability without demanding interference protection

KSAT Design Limitations

• All KSAT systems locked at DAL E due to market size; providers won't develop higher design assurance levels for aviation
• Only addressing loss of function hazard; misleading data handled at application level, not radio layer

Operational Dependencies

Airlines' Growing Reliance

• Connectivity becoming operationally critical beyond passenger services
• Loss of broadband increasingly disruptive to airline operations themselves
• Connected Application Server enabling low-barrier third-party app development for airlines (similar to EFB iPad ecosystem)
• Containerized software architecture with access to aircraft data buses

Geographic Coverage Challenges

• China and other nations restrict satellite operations; Starlink unlikely to gain Chinese approval
• Dual networks required to ensure global coverage across all airline routes

Historical Context

• Satcom voice certification timeline: 1990 first ACARS, 1993 voice capability, 1994 working group DO-222/DO-231 published
• 33 years later voice side remains "stuck" while data progressed
• HF communications dating to 1908 Wright Brothers airplane; time to transition off HF
• HYCON ATM initiative using KSAT in supplementary mode to offload L-band networks

Market Consolidation Risks

Spectrum Acquisition Activity

• SpaceX IPO at $1.75 trillion valuation, raising $50 billion
• Starlink purchased $17 billion spectrum from Dish Network
• Reported Amazon acquiring Globalstar for $9 billion primarily for spectrum rights
• Direct-to-device market projected as $100+ billion opportunity
• ViaSat and Iridium market caps under $10 billion; potential acquisition targets for spectrum
• Note: ViaSat and Iridium remain fully committed to aviation; no current acquisition activity

Future Technologies

• Space-based VHF voice for communications
• Q/V-band and free-space optical links for aircraft (long-term)
• Alternative PNT services overlapping communications to address GPS jamming/spoofing
• Fiber optics pivot for new aircraft programs

Open Questions

• Can performance-based approach overcome AMSS spectrum restrictions for safety services without interference protection guarantees?
• Will regulators approve two diverse and independent KSAT systems to provide a single required radio service?
• Will aircraft manufacturers provision for dual server architecture to enable true fail-over capability?

Stay tuned!

 

 

Peter Lemme

 

peter @ satcom.guru

Copyright 2026 satcom.guru All Rights Reserved

 

Peter Lemme has been a leader in avionics engineering for 43 years. He is the thought leader to the Seamless Air Alliance. He offers independent consulting services largely focused on avionics and L, Ku, and Ka band satellite communications. Peter chaired the SAE-ITC AEEC Ku/Ka-band satcom subcommittee for more than ten years, developing ARINC 791 parts 1, 2, and 3; ARINC 792, Project Paper 793, and continues as a member. He also contributes to the Network Infrastructure and Cybersecurity (NISC) subcommittee.

 

Peter was Boeing avionics supervisor for 767 and 747-400 data link recording, data link reporting, and satellite communications. He was an FAA designated engineering representative (DER) for ACARS, satellite communications, DFDAU, DFDR, ACMS and printers. Peter was lead engineer for Thrust Management System (757, 767, 747-400), also supervisor for satellite communications for 777, and was manager of terminal-area projects (GLS, MLS, enhanced vision).

 

An instrument-rated private pilot, single engine land and sea, Peter has enjoyed perspectives from both operating and designing airplanes. Hundreds of hours of flight test analysis and thousands of hours in simulators have given him an appreciation for the many aspects that drive aviation; whether tandem complexity, policy, human, or technical; and the difficulties and challenges to achieving success.