Week 43 (19–25 October 2026): Integrity-drop measurements (consistent with GNSS degradation)

Findings this week

1. In the regional scope (Türkiye and neighbours), 3.82% (6,630) of 173,485 aircraft-hours over seven days showed degraded navigation integrity; the daily rate ranged from 3.06% to 4.25%. The peak day was 22 October (4.25%), followed by 23 October (4.16%). These data do not identify the cause of any rise or fall.
2. Share of aircraft affected by region (weekly, FIRs with sufficient observation volume): Ankara 9.4%, Damascus 8.7%, Bucharest 7.4%, Sofia 4.8%, Istanbul 3.4%.
3. The integrity-drop event affecting the most aircraft this week was on 24 October in the Istanbul FIR: 160 unique aircraft, 5 hours (01–05 UTC), 37 cells (event = connected medium/high-level cell-hours). The days of the week were produced with several algorithm versions (1.10.0, 1.6.0); the level and event rules are identical across them, so events are comparable; only the position-anomaly confidence tiers and the exclusion of faulty-avionics aircraft were computed differently between versions, so small count differences between days are possible.
4. Position anomalies (spoofing, rule-based, focus region): 39 high/medium-confidence events this week (30 high, 9 medium); busiest day 23 October (11). There are also 21 low-confidence events and 308 jumps overlapping with low integrity; jumps coinciding with integrity loss are not counted in this headline figure; the cause is not stated. Indicator only: it states no cause.