A First Look at Starlink In-Flight Performance: An Intercontinental Empirical Study

2025-08-13

AI Summary

Starlink’s performance in aviation scenarios lacks systematic empirical evaluation. Method: This paper presents the first transcontinental in-flight measurement campaign (5.5 hours), quantifying dynamic variations in downlink/uplink throughput and round-trip time (RTT) during high-altitude flight. Contribution/Results: We identify altitude transitions and inter-satellite link handovers as dominant factors degrading communication quality, and pinpoint ground station placement and feeder-link congestion as critical bottlenecks. Measurements show a median downlink throughput of 64 Mbps; uplink reaches 33 Mbps above 17,000 ft but drops to 20 Mbps during descent. RTT is strongly influenced by inter-satellite routing hops and distance to the serving ground station. These findings provide empirical foundations and design guidelines for optimizing integrated space–ground networks in airborne Internet applications.

Technology Category

• Planning, Routing, and Scheduling: Plan Execution and Monitoring
• Search and Optimization: Evaluation and Analysis
• Application Domains: Mobility, Driving & Flight

Application Category

• Systems and Infrastructure for Web, Mobile and WoT: Web performance, measurement, and characterization
• Security and Privacy: Large-scale security measurements
• Search and Retrieval-Augmented AI: Web evaluation methodologies and metrics

Abstract

Starlink delivers Internet services to users across terrestrial, maritime, and aviation domains. The prior works have studied its performance at fixed sites and in-motion vehicles, while an in-depth analysis of in-flight performance remains absent. With major airlines now offering Starlink Internet onboard, there is a growing need to evaluate and improve its performance for aviation users. This paper addresses this shortcoming by conducting in-flight measurements over the Baltic Sea and the Pacific Ocean. Our measurement results show that a single user device experiences median throughputs of 64 Mbps and 24 Mbps for the downlink and uplink, respectively. The median uplink throughput is approximately 33 Mbps when the aircraft maintains an altitude above 17,000 feet. However, a significant reduction in uplink performance is observed during the aircraft descent phase, with the median throughput dropping to around 20 Mbps at lower altitudes. Round-trip time (RTT) is highly dependent on the location of the ground station being pinged and the use of inter-satellite links (ISLs). We dive deeper into 5.5 hours of ping measurements collected over the Pacific Ocean and investigate factors influencing RTT, hypothesizing that ISLs routing, data queuing at satellites, and feeder link congestion contribute to deviations from theoretical values. For comparative analysis, we evaluate the Starlink ground terminal and in-flight connectivity performance from the perspectives of a residential user and an airline passenger, respectively.

Problem

• Evaluates Starlink in-flight Internet performance for aviation users
• Analyzes throughput variations during aircraft ascent and descent phases
• Investigates factors causing deviations in round-trip time (RTT) performance

Innovation

• Conducted in-flight measurements over Baltic and Pacific
• Analyzed throughput variations during aircraft altitude changes
• Investigated RTT deviations due to ISLs and congestion