Was his pattern a year ago with dictated sentences, or original sentences? What kind of spelling errors is he making in isolated spelling? Are they dysphonetic? Phonetic equivalents? Homophone errors? Given that he is able to correct his spelling errors when cued, is he using the context of the sentence to cue self-corrections? Does he repeat both the dictated words and sentences out loud before writing them? Either? Neither?

...pronounced like the long vowel and first letter of the alphabet...