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Week 2026 / 39 · 2026-09-21 – 2026-09-27

Week 39 (21–27 September 2026): Integrity-drop measurements (consistent with GNSS degradation)

Indicative · based on ADS-B integrity (NIC) data

Affected aircraft-hour share

%3.1

▲ 0.1 pp vs previous week

Affected aircraft-hours

5,644

/ 180,203 aircraft-hours

Events

220

220 medium/high sufficiency

Position anomalies

263

high/medium-sufficiency events

Day by day

Each day's affected aircraft-hour share (%). Peak day in dark colour.

  • 3.1
    Mon
  • 2.7
    Tue
  • 3.5
    Wed
  • 3.2
    Thu
  • 2.9
    Fri
  • 3.2
    Sat
  • 3.4
    Sun

Last 12 weeks

Weekly share; this report is the highlighted point. Weeks without data are left blank.

%3.1%4.1

Highest FIRs

Regions with enough sample during the week, by affected aircraft share.

  • Damascus%8.5
  • Ankara%7.1
  • Bucharest%6.5
  • Amman%3.9
  • Sofia%3.6
  • Nicosia%3
  • Istanbul%2.8
  • Cairo%2.3

Cell map of the peak day · 2026-09-23

Each polygon is an H3 cell; “no data” does not mean calm.

  • Insufficient data
  • Low
  • Medium
  • High

Largest event of the week

Istanbul

141

2026-09-21, 00–09 UTC, 10 hours in total. The number of unique affected aircraft is shown above.

Position anomalies (spoofing) · day by day

High- and medium-sufficiency events (rule-based, focus region only); high in dark colour.

  • 0
    Mon
  • 12
    Tue
  • 61
    Wed
  • 21
    Thu
  • 111
    Fri
  • 23
    Sat
  • 35
    Sun

Findings this week

  1. In the regional scope (Türkiye and neighbours), 3.13% (5,644) of 180,203 aircraft-hours over seven days showed degraded navigation integrity; the daily rate ranged from 2.74% to 3.51%. The peak day was 23 September (3.51%), followed by 27 September (3.37%). 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): Damascus 8.5%, Ankara 7.1%, Bucharest 6.5%, Amman 3.9%, Sofia 3.6%.
  3. The integrity-drop event affecting the most aircraft this week was on 21 September in the Istanbul FIR: 141 unique aircraft, 10 hours (00–09 UTC), 28 cells (event = connected medium/high-level cell-hours). All days of the week were produced with the same algorithm version (1.5.0), so the events are comparable with one another.
  4. Position anomalies (spoofing, rule-based, focus region): 263 high/medium-confidence events this week (263 high, 0 medium); busiest day 25 September (111). There are also 8 low-confidence events and 498 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.
Data period, version and scope

This report was published on 15 October 2026 and rests on the published data of that day: regional scope (Türkiye and neighbours), algorithm 1.5.0 (a single affected-aircraft definition is used: a notable share of reports showing low integrity; faulty-transmitter filter applied). This report was prepared retrospectively on 15 October 2026, after the week ended: the figures show the current reprocessed series, not necessarily what would have been published at the time. Earlier weekly reports may have been prepared with a different scope or algorithm version; reports must not be compared directly. The data come from a single source (adsb.lol); areas without receivers are invisible and “no data” does not mean “calm”. It is an indicator only: it states no cause and makes no definitive detection claim.

Open on the map

This report is based on observed ADS-B data and is not an operational navigation source. See the methodology page for the general framework.