The /ɑ/ vowel is usually spelled <ar> but we also find <a> in ma, <aa> in baa and the letter name R. The /eə/ diphthong is spelled <air>, <are>, or <ear> in tear.
This contrast is between a long vowel and a diphthong. The starting tongue positions are fairly well separated and confusions are unlikely.
Interesting pairs include:
barley barelyThe second of these pairs is famously incorporated into a classic joke, a newspaper correcting a misprint in which instead of writing about a soldier "he was a battle-scarred warrior" it had printed "battle-scared" and then miscorrected it to "bottle-scarred"
The density value is 7.58%. The pairs make 34 semantic contrasts, giving a loading of 46.6%.
afar affair aria area arias areas baa bare baas bares baa'd bared baa bear baas bears bar bare barring baring barred bared bars bares bar bear barring bearing bars bears barley barely barn bairn barns bairns car care cars cares card cared char chair charred chaired charring chairing chars chairs fa fair fa fare far fair far fare hard hared khan cairn khans cairns lard laird lards lairds ma mare mas mares mar mare mars mares pa pear pas pears pa pair pas pairs par pair pars pairs parr pear parrs pears parr pair parrs pairs R Ayr R's airs scar scare scarred scared scarring scaring scars scares shah share shahs shares shard shared spar spare sparred spared sparring sparing spars spares star stair starred stared starring staring stars stairs ta tare ta tear tar tare tars tares tar tear tarring tearing tars tares yah yeah
John Higgins, Shaftesbury, November 2009