Mile High WiFi: A First Look At In-Flight Internet Connectivity

In-Flight Communication (IFC), available on a growing number of commercial flights, is often received by consumers with both awe for its mere availability and harsh criticism for its poor performance. Indeed, IFC provides Internet connectivity in some of the most challenging conditions with aircraft traveling at speeds in excess of 500 mph at 30,000 feet above the ground. Yet, while existing services do provide basic Internet accessibility, anecdotal reports rank their quality of service as, at best, poor. In this paper, we present the first characterization of deployed IFC systems. Using over 45 flight-hours of measurements, we profile the performance of IFC across the two dominant access technologies – direct air-to-ground communication (DA2GC) and mobile satellite service (MSS). We show that IFC QoS is in large part determined by the high latencies inherent to DA2GC and MSS, with RTTs averaging 200ms and 750ms, respectively, and that these high latencies directly impact the performance of common applications such as web browsing. While each IFC technology is based on well studied wireless communication technologies, our findings reveal that IFC links experience further degraded link performance than their technological antecedents. We find median loss rates of 7%, and nearly 40% loss at the 90th percentile for MSS, 6.8x larger than recent characterizations of residential satellite networks. We extend our IFC study exploring the potential of the newly released HTTP/2 and QUIC protocols in an emulated IFC environment, finding that QUIC is able to improve page load times by as much as 7.9 times. In addition, we find that HTTP/2’s use of multiplexing multiple requests onto a single TCP connection performs up to 4.8x worse than HTTP/1.1 when faced with large numbers of objects. We use network emulation to explore proposed technological improvements to existing IFC systems finding that high link losses, and not bandwidth, account for the largest factor of performance degradation with applications such as web browsing.