US aircraft privacy is not enforced in the air — it lives in a contract attached to the FAA’s data feed. LADD does not silence a transponder; it obliges vendors using FAA SWIM data to stop redistributing what they pulled from that feed.
Because the obligation travels through the data pipe, an independent, community-fed tracker that never touches FAA data sits outside it. The same aircraft can be invisible on one app and plainly visible on another. The broadcast itself never changed.
On August 17, 2018, an email account associated with SpaceX asked the FAA to block aircraft N628TS — the jet linked to Elon Musk — from distribution through the LADD program. The records surfaced later through a FOIA disclosure. What they showed was less a secret than a diagram of how aircraft privacy actually works.
Nothing about the jet’s transponder changed. It kept broadcasting identity, position, altitude, and speed over an open, unencrypted frequency.
What changed was which apps were allowed to repeat what the FAA’s data pipe carried. Any receiver network outside that pipe could still hear the aircraft and display it. The result is the patchwork a traveler sees every time two flight trackers tell different stories about the same flight.
LADD is a distribution rule, not a radio rule
The FAA’s Limiting Aircraft Data Displayed program — LADD — lets an aircraft owner ask the agency to keep a tail number out of its external data distribution. The request requires a registration number or call sign and an ICAO Mode S address. Once filed, the aircraft is filtered at the FAA source for outside vendors.
What the program does not do is touch the signal. An ADS-B Out broadcast keeps going out in the clear, unchanged, whether or not the FAA feed carries it.
Nothing about LADD alters that. The strongest setting the agency describes — FAA-source blocking — keeps data available for the FAA’s own use while withholding it from external vendors receiving the FAA feed.
The obligation itself comes from a contract, not legislation. According to the Federal Aviation Administration, SWIM subscribers operate under a Data Access User Agreement that requires them to filter LADD participants from public display. The program page states that LADD implements Section 803 of H.R. 3935, the FAA Reauthorization Act, and provides filtering through the FAA SWIM data feed or participating websites.
Why a community-fed network never touches FAA data
FlightAware and Flightradar24 each combine an FAA data feed with their own volunteer receiver networks. That dual-source model is precisely why LADD can reach them: when they display data covered by the FAA feed terms, the filter obligation rides along. A separate governance document puts the rule plainly — users publicly displaying SWIM data must apply the LADD filter under the SCDS Service Access Agreement, as the Federal Aviation Administration (FAA) states.
ADS-B Exchange is built on a different architecture. Its model is collaborative: volunteers run their own receivers and feed what they pick up to the platform, which then publishes it, according to Radio Hangar.
There is no FAA pipe upstream, no feed terms of use, and no LADD relationship documented in the reviewed materials. The network exists because ADS-B travels in the clear and cheap software-defined radio gear puts reception within reach of just about anyone.
What is not publicly documented is the internal plumbing: how the platform validates messages, weights sources, and suppresses duplicate hits. That engineering detail is absent from its public materials, which means the model can be described but not fully audited from the outside.
| Service | FAA SWIM feed documented | LADD obligation documented |
|---|---|---|
| FlightAware | Yes — identified as combining FAA data with its own receiver network. | Yes, when displaying data covered by the FAA feed terms. |
| Flightradar24 | Yes — identified as combining an FAA feed with its own receiver network. | Yes, when displaying data covered by the FAA feed terms. |
| ADS-B Exchange | No FAA SWIM feed documented; stated model is a collaborative contributor network. | No LADD obligation identified; does not rule out another legal process. |
| Source: Federal Aviation Administration (FAA); ADS-B Exchange | ||
The clearest contrast in the table is the third row. ADS-B Exchange is the outlier not because it refuses a request — there is no evidence of that — but because the obligation was never attached to the data it ingests. The aircraft-owner request travels through FAA channels; a network that never connects to those channels never encounters it.
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One spread in the feeder numbers no one should quote as fact
ADS-B Exchange advertises network totals above 20,000 or 25,000, depending on which page you read, and it uses three different words for the same idea: contributors, feeders, receivers. Older secondary reporting circulates a 5,000–7,000 figure for active feeders. None of those totals counts receivers that are live at the same moment, and the reviewed materials settle on no stable real-time metric.
The honest version: feeder activity and uptime exist on leaderboards, but any single hard figure shifts with definitions, time, and measurement method. This article declines to repeat one as settled. That variance is not evasion — it is the actual state of the platform’s public documentation.
How the contract actually reaches a flight tracker
LADD works as a control on distribution, not on transmission. An owner asks the FAA to filter a named aircraft’s information before or during delivery through SWIM.
The agency’s 2024 SWIM governance guidance then binds anyone publicly displaying SWIM data to apply that filter under the SCDS Service Access Agreement. The aircraft’s avionics, meanwhile, keep transmitting as they always did.
That split is what produces the mismatch a traveler notices: one app drops the aircraft because it respects the FAA feed restriction, while the other shows it because its data came from receivers outside that feed. The two are not disagreeing about the aircraft; they are answering different questions about where the data came from.
The N628TS case is the best-documented illustration of the mechanism’s limits. The request pulled the jet out of FAA distribution to outside vendors — and stopped there. Nothing in the public record shows a non-FAA service being forced to hide the aircraft.
The open question is what could reach a non-FAA aggregator. The reviewed FAA documents, court records, and FCC material identify no comparable instrument. That absence does not prove a non-SWIM aggregator could never be compelled — a separate court order or statute could still do it.
The fact base supports saying the FAA’s current LADD duty stops at the data pipe. It does not support claiming nothing else ever could.
What this means for you
The most useful habit is to stop treating a missing tail number as an app error. When an aircraft appears on one tracker and not another, you are seeing the difference between a feed contract and a volunteer receiver network. That discrepancy is policy, not malfunction.
For owners and operators of business or private aircraft, the protection on offer is partial by design. No request to the FAA controls a signal being captured by a private receiver. LADD changes the distribution of FAA data; it does not silence the broadcast.
Key terms
- LADD
- LADD — Limiting Aircraft Data Displayed — is an FAA program that lets an aircraft owner ask the agency to keep a tail number out of its external data distribution. A request requires the aircraft’s registration number or call sign and an ICAO Mode S address, and the program implements Section 803 of H.R. 3935, the FAA Reauthorization Act. Because the filter is applied at the FAA source, it reaches only vendors that draw on FAA data — a limit that shapes how much protection a LADD request actually delivers.
- SWIM
- SWIM is the FAA’s data-distribution system, which publishes air-traffic data to approved consumers through subscription or on-demand services. Vendors that publicly display SWIM-derived data must apply the LADD filter under the applicable service-access terms. That contract is what gives LADD its reach: the obligation rides on the data feed, so it binds only the services that connect to it.
- ADS-B Out
- ADS-B Out is the broadcast an aircraft sends carrying its identity, position, altitude, and speed over an open, unencrypted frequency. Because the signal travels in the clear, anyone with a receiver — including volunteer networks — can pick it up. It is the reason a LADD request cannot make an aircraft disappear from every screen: the signal keeps going out even when the FAA feed stops carrying it.
- Mode S address
- A Mode S address is the unique identifier an aircraft’s transponder broadcasts, used to tell one aircraft from another in surveillance data. The FAA requires it, along with a registration number or call sign, when an owner files a LADD request. Because it is tied to the airframe rather than the flight, it is the piece of data a filter has to match to suppress a specific aircraft.
Questions? Answers.
Can the FAA tail number be blocked?
An aircraft owner can file a LADD request with the FAA using the registration number or call sign and the ICAO Mode S address. The strongest setting withholds the aircraft from external vendors receiving the FAA feed while keeping it available for FAA use.
How to track planes that are blocked?
Planes blocked at the FAA source can still be picked up by independent receiver networks outside the FAA feed, because the ADS-B broadcast itself is unchanged. A community-fed tracker such as ADS-B Exchange may display the aircraft from volunteer receiver data.
Does Flightradar24 honor LADD requests?
Yes, when displaying data covered by FAA feed terms. Flightradar24 combines an FAA data feed with its own volunteer receiver network, and the SWIM access terms require the LADD filter for FAA-derived data. Aircraft captured only through non-FAA receivers may still appear.
Why might a flight be missing from one tracking app but visible on another?
The apps can draw from different data pipes. One may be filtering the aircraft because its data came from the FAA feed and the LADD filter applies. Another may be displaying the same aircraft from a community-fed receiver network outside that feed.
