Grimes resorted to tracking Elon Musk's private jets in attempt to serve him with custody papers

• Grimes paid multiple process servers to try to deliver a lawsuit to Musk.
• One process server used a jet-tracking to try to serve Elon Musk with the custody papers.
• Grimes is suing Musk for physical custody of their three children.

A person hired by Grimes' legal team tracked Elon Musk's private jets for days in an attempt to serve him with custody papers, according to court documents obtained by Insider.

A lawyer for Grimes filed a supplemental proof of service document in a California court on November 3. The court document showed that over the course of a week in October, multiple process servers — people hired to deliver legal documents to defendants — attempted to deliver custody papers to Musk at several locations, including X's headquarters, Tesla's Texas gigafactory, and SpaceX's launch site in Boca Chica, Texas.

The process servers were not able to deliver the papers personally to Musk and were only able to serve the documents via substituted service — when papers are left with someone else at a person's home or business rather than the person themself — according to the court documents.

Grimes is suing Musk for physical custody of her three children that Musk fathered. The artist, whose legal name is Claire Boucher, told a Texas court last month that Musk has physical custody of one of her children, X Æ A-XII, "over [her] objection."

She has asked a Texas court to throw out a separate lawsuit from Musk that he filed prior to Grimes' custody suit. The billionaire had sued Grimes in September to "establish the parent-child relationship" with his children.

Musk and lawyers for Musk and Grimes did not immediately respond to Insider's requests for comment on Thursday.

In Grimes' latest filing, she documented numerous attempts to serve Musk with the custody papers. Over the course of a week, four different process servers attempted to track down the billionaire, the court records show.

One process server even followed the whereabouts of Musk's private jets from October 13 to 17, writing that Musk "utilizes his aircraft to such an extent that his travel on his owned aircraft has been likened to a rideshare, such as Uber."

Musk has been known to use his private jets to fly between his companies, including Tesla's headquarters in Texas and X's in San Francisco.

The process server said in the court documents that she was initially unable to track Musk's private jets using sites, like FlightAware, which receive their data via the Federal Aviation Administration. Insider previously reported Musk utilizes an FAA feature called the "Limited Aircraft Data Displayed" program or LADD to cloak his travel. The LADD list prevents flight data from being shown on sites that use FAA data and is used by several celebrities and public figures, including Jeff Bezos and Taylor Swift.

Up until recently, the billionaire had also attempted to dodge jet-tracking by using another FAA system designed to hide private jet travel, the privacy ICAO aircraft address program, also known as PIA.

But Insider reported Musk gave up on the system in December after it was unable to prevent people from tracking his jets on social media.

Similarly, the process server said in the court documents she was able to track Musk's jets using "crowdsourced data, collected from radio signals transmitted from aircraft."

Jet-trackers are able to get around FAA programs like the LADD list by using sites like the ADS-B Exchange, a public flight-tracking database that collects data from a network of volunteer-run radios or "feeders" that transmit data from ADS-B-equipped aircraft. (ADS-B is a surveillance technology that broadcasts information like a plane's GPS location and altitude from one aircraft to another, as well as to ground stations.)

Musk has spoken out against jet-tracking in the past, famously offering a college student who posted his jet travels on social media $5,000 to stop sharing his flight data and then later temporarily banning that same student on X.

The process server said she even set up "surveillance positions" near hangars and along the runway at an airport in Hawthorne, California, when one of Musk's jets flew to the location on October 16, but the server was unable to connect with Musk directly, according to the court documents.

Christopher Melcher, a California family law attorney and partner at Walzer Melcher, told Insider that the use of jet tracking by the process server was unusual but not unreasonable.

"Typically we don't have any knowledge of the comings and goings of these people, so it's reasonable to knock on their door or go to their place of business" and expect them to be there, he said.

However, if there is publicly available information that shows Musk is in another state or country, like the jet-tracking data, it wouldn't be reasonable to show up at his home and expect to be able to hand deliver papers to him.

In her court papers, Grimes' team said a different process server who had handed her complaint to Musk's security at X was proof enough that she'd served the billionaire.