Mysterious gauge on the Sukhoi Superjet PFD

The Sukhoi Superjet 100 (SSJ100) primary flight display features a small indicator positioned to the left of the speed tape that has drawn attention from pilots and enthusiasts for its unfamiliar appearance relative to conventional Western glass cockpit layouts. Based on the described behavior — steady indication near the value 5 during approach and landing, followed by an abrupt snap to zero several seconds after main gear touchdown — the instrument is consistent with an **angle of attack (AoA) indicator**. A typical stabilized approach on a regional jet generates an AoA of approximately 4–6 degrees relative to the aircraft's zero-lift reference, which aligns precisely with the observed reading. The sharp transition to zero occurs as the nosewheel settles onto the runway surface and the aircraft geometry flattens, collapsing the effective AoA to near-zero.

The SSJ100's close visual resemblance to the Airbus PFD is not coincidental. The aircraft was developed through extensive partnership with Western suppliers — Thales serves as the primary avionics integrator, and the flight deck philosophy was deliberately aligned with Airbus human-machine interface conventions to ease type transitions for European and Latin American operators. However, Thales incorporated the AoA display in a position and format that has no direct equivalent on the standard Airbus A320-family PFD, where AoA is not explicitly shown as a dedicated primary display element. The SSJ100 design reflects a Russian certification philosophy that has traditionally emphasized discrete AoA awareness as a primary crew reference, a heritage tracing back to Soviet-era transport aircraft where AoA instruments were standard fitment on the panel.

For pilots transitioning to the SSJ100 — particularly those coming from Airbus or Boeing backgrounds — the presence of a real-time AoA readout on the PFD represents both a philosophical and procedural difference. Western transport operations have long relied on airspeed and attitude as the primary energy-state references, with AoA managed implicitly through Vref and configuration. An explicit AoA display on the primary scan demands awareness during type training: crews must understand what the indicator is showing, its normal range during each phase of flight, and crucially, that a snap-to-zero reading post-touchdown is normal system behavior rather than a sensor anomaly. Failure to understand the instrument during initial qualification could generate unnecessary go-around decisions or post-landing confusion.

The broader relevance extends to ongoing industry discussions about AoA display and crew awareness following high-profile accidents. The aftermath of the Boeing 737 MAX MCAS failures renewed regulatory and manufacturer interest in making AoA data more accessible to flight crews, and several avionics manufacturers now offer optional AoA indexers or tape displays for retrofit on existing transport-category aircraft. The SSJ100's factory-installed AoA indication on the PFD positions it ahead of most Western contemporaries in this regard, even if the implementation remains largely unfamiliar to crews trained exclusively on Airbus or Boeing equipment. As fleet operators continue evaluating AoA display as a safety enhancement, the SSJ100's approach offers a practical case study in integrating that information into the primary scan without requiring crew workload to shift away from conventional speed and attitude references.